The atomic bomb was invented by the Manhattan Project, a massive scientific research program led by the United States during World War II. The project involved over 130,000 people and was headed up by physicist J. Robert Oppenheimer. However, the work of physicist Leo Szilard was also instrumental in getting the project started earlier. Szilard had the initial idea that a nuclear chain reaction could be used for a bomb and pushed hard to get funding, partnering with Albert Einstein to convince the US government to fund nuclear weapons research. This ultimately led to the creation of the Manhattan Project and the invention of the atomic bomb years earlier than may have otherwise occurred.

1. Science Topics
Education Topics
Quizzing Students on the Myths of Science
10/29/2004 - Eugene L. Chiappetta and Thomas Koballa
While an impressive body of content knowledge is associated with science
courses, there is more about the scientific enterprise itself that students should
learn. In addition to viewing science as a body of knowledge, students should
also view science as a way of thinking and investigating and should have an
understanding of how science interacts with technology and society
(Chiappetta and Koballa 2002). The most complete science education
experience must give students opportunities to learn about the very nature of
science (NOS).
So what is the nature of this enterprise that we call science? How does science
differ from other ways of knowing? And, how can science teachers help students develop a deep
and rich understanding of science that depicts its true nature? These questions are addressed in
science education documents including the National Science Education Standards (NSES),
which states “Science is a way of knowing that is characterized by empirical criteria, logical
argument, and skeptical review. Students should develop an understanding of what science is,
what science is not, what science can and cannot do, and how science contributes to culture”
(NRC 1996, 21).
The American Association for the Advancement of Science places great emphasis on teaching
and learning about NOS throughout the grades. Science for All Americans: Project 2061
promotes the belief that the world is understandable and although scientific ideas are subject to
change, scientific knowledge is durable (AAAS 1990). While science relies heavily on evidence,
it also requires logic and imagination to form valid conclusions. Science is a complex social
activity that is organized into many disciplines.
Given the emphasis placed on high-stakes testing of students’ science understandings by many
states, great pressure exists to teach content and to prepare students to demonstrate their
knowledge on paper-and-pencil tests. Nevertheless, we urge high school science teachers to
incorporate other facets of science into their courses and recommend that teachers
 teach and assess many aspects of science—content knowledge, process skill
development, attitudes toward science, and how science works; and
 check for students’ understanding of NOS throughout a course—at the beginning of a
teaching session, during lectures, discussions, and laboratory work, and at the end of
lessons and units of study.
One way to promote better understanding of science is to study myths of science by teaching,
testing, and reflecting on these ideas at many points during instruction. We have taken the core

2. ideas of NOS [provided by William F. McComas in this issue of The Science Teacher], modified
some ideas and incorporated others, and developed a “Myths of Science” quiz for students
(Figure 1) that may be useful both as an assessment tool and advance instructional organizer.
Some of the quiz statements represent myths regarding NOS, while others more accurately
reflect NOS. These statements provide an engaging focus on faulty notions of how authentic
science really functions.
Explaining the quiz items
Figure 1 presents a true/false quiz on some myths of science held by many individuals. Before
continuing on with this article, take the quiz yourself and write a few sentences to support your
evaluation of each statement (the answers are available at the end of this article). After
completing the quiz, read the rest of the article as preparation for helping students distinguish
between myths and more correct statements about NOS. (Note: Throughout this article we will
refer to the specific statements in Figure 1 by number.)
Figure 1. “Myths of Science” quiz.
Directions:
Each statement below is about science. Some statements are true and
some are false. On the line in front of each statement, write a “T” if it is
true and an “F” if false. Then support your response to each statement
with at least one paragraph on a separate sheet of paper.
___ 1. Science is a system of beliefs.
___ 2. Most scientists are men because males are better at scientific
thinking.
___ 3. Scientists rely heavily on imagination to carry out their work.
___ 4. Scientists are totally objective in their work.
___ 5. The scientific method is the accepted guide for conducting
research.
___ 6. Experiments are carried out to prove cause-and-effect
relationships.
___ 7. All scientific ideas are discovered and tested by controlled
experiments.
___ 8. A hypothesis is an educated guess.
___ 9. When a theory has been supported by a great deal of scientific

3. evidence, it becomes a law.
___ 10. Scientific ideas are tentative and can be modified or disproved,
but never proved.
___ 11. Technology preceded science in the history of civilization.
___ 12. In time, science can solve most of society’s problems.
Many students, science teachers, and the general public often believe that science is a
systemof beliefs (Statement 1). One of the distinguishing aspects of the scientific enterprise is
its continuing search for evidence in natural phenomena. Although humans have the inclination
to look for evidence to support their ideas in many pursuits, not just in science, scientific ideas
are established only after compelling evidence has accumulated from observations of nature.
Scientists use reasoning and imagination, study the work of other scientists, and collaborate with
other professionals, always looking for evidence to support or disprove their ideas. Rather than a
belief system, science is based on empirical evidence provided by observations of the natural
world.
The idea that science is a male domain (Statement 2) is more a remnant of historical prejudice
than a true understanding of the history and nature of science. Societal attitudes have often made
it difficult for girls and women to pursue science, to the point that a female scientist like
astronomer Caroline Herschel (1750–1848) needed to rely on her brothers William and John to
disseminate her research. But there is no evidence that men are inherently better at science.
Although women are still underrepresented in some fields, women like Marie Curie, Rosalind
Franklin, Barbara McClintock, Dian Fossey, Dorothy Crowfoot Hodgkin, Lise Meitner, and
many others stand among the giants of modern science.
There can be no doubt that scientists rely heavily on their imagination in carrying out their
work (Statement 3); the creative imagination has always been an important part of science.
August Kekule’s visualization of the molecular shape of benzene—often called the crowning
achievement of nineteenth century theoretical organic chemistry—is thought to have been partly
the result of his prior training in architecture. Scientists draw upon their imagination and
creativity to visualize how nature works, using analogies, metaphors, and mathematics.
However, scientists are often stereotyped as bespectacled, serious-looking individuals in lab
coats, conducting laboratory experiments that require superior intellect to be understood. Further,
many people believe that scientists are totally objective in their work (Statement 4). Scientists,
like all humans, are attached to their work and look for evidence to support their favored or
promising ideas, sometimes overlooking and even rejecting ideas that are contrary to their own
beliefs.
During the past 50 years, philosophers of science and science educational researchers have
attempted to dispel the notion of a scientific method (Statement 5). The idea of “a method of
science” has established a hold in science teaching but not in science itself. Posters are still
hanging up in science classrooms that list the steps of the scientific method and these steps are
still used to judge students’ procedures in science fair competitions. We need to be reminded that

4. although scientific papers seem to follow the scientific method, they are reconstructed to account
for key elements of the study. The actual sequence of events for any investigation varies
considerably and may take many wrong turns, encountering many dead ends.
The scientific method is carried out to prove cause-and-effect relationships (Statement 6). At
first, this statement seems correct. Upon reflection, however, the statement is flawed. In
mathematics, theorems are proven and in television courtroom scenes the term proof is used
freely. In science, though, nothing stands as proven or completely true. Controlled
experimentation only provides evidence that either supports or fails to add support to a
hypothesis, not absolute proof. The reasoning, collaboration, and argumentation, as well as
empirical evidence, all contribute to cause-and-effect understandings that are durable but
tentative, always awaiting further evidence.
While controlled experiments can offer compelling evidence to support a hypothesis or theory, it
is a myth to believe that the most credible scientific theories are supported by controlled
experiments (Statement 7). Not all of the support for theories comes from experimentation. For
example, the theoretical basis of the evolution of species, the expansion of the universe, and the
movement of plates in Earth’s crust were developed by studying phenomena through observation
rather than through the manipulation of variables. Science advances from many types of
investigative evidence, which are subject to scrutiny and argumentation by the scientific
community. Historical and observational methods of study are very much a part of authentic
science.
It is often said that a hypothesis is an educated guess (Statement 8). A hypothesis holds a more
rigorous position in science than a mere guess. A guess is usually thought of as a judgment put
forth with little information. However, scientists usually possess a considerable amount of
knowledge about a phenomenon before they form a hypothesis to be tested. “In the scientific
world, the hypothesis typically is formulated only after hours of observation, days of calculating
and studying, and sometimes years of research into the phenomena of interest” (Galus 2003).
Some people believe that when a theory has been supported by a great deal of scientific
evidence, it becomes a law (Statement 9). Laws and theories are distinct types of knowledge
and therefore, laws do not become theories nor do theories become laws. A law is used to
describe a phenomenon or pattern in nature. Laws hold true under most conditions, but can be
modified or discredited. A theory is used to explain a phenomenon. Theories pertain to complex
events that were initiated many years in the past, occur over long periods of time, relate to very
small entities, or exist at great distances from us. In addition, theories combine many facts,
concepts, and laws to form scientific understandings. A good example of this is the law of
conservation of mass in chemistry and the atomic theory used to explain it.
Theories are tentative and can be modified or disproved, but never proved (Statement 10).
This is the flipside of Statement 6 and is a true statement because while scientific theories are
shored up by considerable evidence, they all are considered provisional and subject to change or
rejection. Theories are inferred explanations and science is a way of knowing that does not
represent absolute truth. This way of thinking removes science from being an all-knowing human
enterprise. One philosopher of science, in discussing how knowledge progresses by conjecture,

5. went so far as to assert that: “They may survive these tests; but they can never be positively
justified: They can neither be established as certainly true nor even as ‘probable’ (in the sense of
the probability calculus)” (Popper 1963, vii). However, we should not think of scientific theories
as ideas built on shaky facts and flimsy evidence because many of the major theories of science
have held up to considerable scrutiny and have shown to be durable.
While many individuals believe that technology is the application of science, this is not always
the case. Actually, technology preceded science in the history of civilization (Statement 11).
Civilizations were making tools for survival long before the understandings of these devices
were reasoned out. Technology invents devices and systems to aid in human survival and to
improve life. Science provides a better fundamental understanding of nature. However, today
science and technology are closely associated, whereby technology supports the advancement of
science and science supports the progress of technology. In some cases science precedes
technology, while in other instances technology precedes science.
The statement “In time, science can solve most of society’s problems,” reflects a poor
understanding of the nature and role of science in society (Statement 12). Science has improved
life considerably for many people on the planet. Agriculture, medicine, and electronic
communication have benefited enormously from scientific knowledge, but not everyone in the
world has benefited from these examples of scientific advancement. Many problems in the world
are political in nature, whereby individuals and governments promote or suppress economic and
scientific development in their country. For example, science has provided us with the
knowledge of how to produce enough food to feed most of the world’s hungry, but getting the
food to their mouths is a problem that transcends science.
Sharpening student understanding
This quiz can be used at the beginning of the school year or at any point throughout the year as a
tool to sharpen students’ understanding of NOS. Students can be asked to discuss why some
NOS statements are correct as well as why some are false and to justify their reasoning. Students
need more than content lectures and inquiry-based laboratory exercises to understand authentic
science. Teachers must be explicit when teaching NOS and these ideas must be addressed
directly in the planning, teaching, and assessment of science courses.
Eugene L. Chiappetta (e-mail: echiappetta@houston. rr.com) is a professor in the Department
of Curriculum and Instruction, University of Houston, 256 Farish Hall, Houston, TX 77204; and
Thomas Koballa (e-mail: tkoballa@coe.uga.edu) is a professor in the Department of Science
Education, University of Georgia, 212 Aderhold Hall, Athens, GA 30602.
Answer key to Figure 1:
1-F, 2-F, 3-T, 4-F, 5-F, 6-F, 7-F, 8-F, 9-F, 10-T, 11-T, 12-F
References
American Association for the Advancement of Science (AAAS). 1990. Science for All
Americans: Project 2061. New York: Oxford University Press.

6. Chiappetta, E.L., and T.R. Koballa. 2002. Science Instruction in the Middle and Secondary
Schools. Upper Saddle River, N.J.: Merrill/Prentice Hall.
Galus, P.J. 2003. A testable prediction. The Science Teacher 70(5): 10.
National Research Council (NRC). 1996. National Science Education Standards. Washington,
D.C.: National Academy Press.
Popper, K. 1963. Conjectures and Refutations: The Growth of Scientific Knowledge. New York:
Harper and Row.
5 Share on facebook Share on twitter
Social media dashboard
Sponsored by
Share Question
TwitterFacebookGoogle+
Related Topics
Science, Engineering, and Technology
Social Sciences
History
Who invented the atomic bomb?
Comments2+
Answer Wiki
American scientist J. Robert Oppenheimer and his team at Manhattan Project invented the
atomic bomb
11 Answers
Jay Wacker, History: strictly amateur
12 upvotes by Mark Eichenlaub (PhD student in Physics), Quora User, Yair Livne, (more)
Well the entire Manhattan Project was responsible for the creation of the first functioning atomic
bomb. It required 130,000 people. J. Robert Oppenheimer was at the helm of the Manhattan

7. Project when it succeeded.
From my reading of "The Making of the Atomic Bomb" by Richard Rhodes and my knowledge
of physics and the history of physics, if you were going to look for one person whose
contribution sped up the project by an indeterminate amount of time, it was the work of Leo
Szilard (I believe he was only an advisor to the Manhattan Project and not directly contributing
to it when the project completed). All of the other people mentioned in Quora User's answer
contributed substantially and have a more distinguished scientific legacy; however, Leo Szilard
had a belief that there had to be an element that could undergo a runaway nuclear fission reaction
-- he took his belief from H. G. Wells' science-fiction novel "The World Set Free" (1914). He
really had no real reason to believe this, but he set about finding such a reaction. As Savas
Dimopoulos says, "the origin of a great discovery is knowing one thing that no one else
does." And in 1939 when Otto Hahn and Fritz Strassmann discovered neutrons were released in
fission, Szilard knew immediately what this meant and immediately set off to build an energy
source. Enrico Fermi dismissed the idea as extremely unlikely calling Szilard "Nuts!".
Szilard pushed hard, partnering with Albert Einstein and Edward Teller to get the US
government to fund this research which ultimately led to the creation of the Manhattan
Project. Fermi was cautious and didn't want to over-promise and under-deliver. This would
have put the atomic bomb on a much slower trajectory and it might not have commenced until
after WWII, thereby delaying the atomic bomb potentially by decades (it cost $2B, equivalent to
$24B today over 4 years during the largest war in World history). The USSR wouldn't have put
in the same efforts into nuclear weapons research without the demonstration of Hiroshima and
Nagasaki. The US wouldn't have put the enormous efforts into the hydrogen bomb either.
I should say, that this this is probably not a good thing, though who knows, we might have had
very bloody wars rather than the Cold War. But without Szilard beliefs and going for the
jugular, the atomic bomb and all nuclear physics funding would have been much lower and the
development would have been delayed by an indeterminate period of time.
Updated 20 Oct, 2014. 9,929 views.
Downvote
Comment
More Answers Below.
Related Questions

Who invented the Russian hydrogen bomb?

How many atoms are split in an atomic bomb?


8. Prior to its use in WW2, were any studies conducted on the aftereffects, etc., of the
atomic bomb?
Quora User, electrical engineering graduate stude... (more)
49 upvotes by Jay Wacker (physicist, phd+postdoc+faculty), Quora User, Steve Denton, (more)
The scientific developments that directly led to the first atomic bomb (fission bomb) was the
discovery that you could split an atom in a process called nuclear fission and harness the energy.
The main developments that led to fission and the atomic bomb are as follows:
1. Albert Einstein, in the year 1905, proposed the equivalence of mass and energy with the now
famous expression .
2. Ernest Rutherford proposed in 1911 the atom as consisting of a core called nucleus, consisting
of heavy protons surrounded by electrons. For the atomic bomb, it is only necessary to consider
the nucleus. Around the same time, Neils Bohr and others developed quantum mechanics that
deepened our understanding of the atom.
3. Henri Becquerel discovered spontaneous radioactivity in Uranium, and Pierre and Marie Curie
explained and worked extensively on the concept. This was in the early 1900s.
4. James Chadwick in 1932 discovered that the nucleus also consisted of neutrons and soon, it
was discovered that neutrons and protons are held together by a hitherto unknown kind of force
called the 'strong nuclear force'.
5. Enrico Fermi discovered in 1934 that you can bombard Uranium with neutrons and generate
new elements and energy, in experiments that demonstrate Einstein's mass-energy equivalence.
This phenomenon is called 'induced radioactivity' as opposed to the spontaneous natural
radioactivity discovered and studied by Becquerel and the Curies.
6. Lise Meitner, Otto Hahn, and Fritz Strassman in 1938 discovered the process of nuclear
fission in Germany. This was the experiment that perhaps most directly led to the physics behind
the atomic bomb. Soon after, this experiment was repeated with success in the US.
7. Leo Szilard, a US based Hungarian émigré, discovered in the 1930s that this 'nuclear fission
reaction' can be cascaded into a self-sustaining chain reaction. This made atomic bombs
theoretically possible. Around the same time, Frederic Joliot-Curie and Enrico Fermi also
proposed designs for 'nuclear reactors'- setups to implement nuclear chain reactions. Enrico
Fermi later led the effort to build the first chain reactor on a modified squash court in Chicago in
1942.
At the policy level, around 1939, following the culmination of the above developments,
physicists Leo Szilard, Edward Teller, and Eugene Wigner urged Einstein to write to Franklin D.

9. Roosevelt, the then president of the US about the possibility that the Germans, then in conflict
with the US, would be attempting to build an atomic bomb- a bomb based on the nuclear chain
reaction and having enormous destructive capabilities. The letter delivered to FDR on October
11, 1939 asked FDR to take all steps to secure Uranium supplies from Belgian controlled Congo,
and start a serious government effort to get the scientists together and provide logistical support
to hasten the development of the physics, mathematics, and engineering leading to the atomic
bomb. The letter can be seen at this link: http://upload.wikimedia.org/wiki...
This led to the Manhattan Project, a nationwide effort led by the facility at Los Alamos in New
Mexico, which culminated in the development of the atomic bomb. Robert Oppenheimer was the
scientific director of the Manhattan Project. The work that went on as part of the Manhattan
Project was classified for several years, but with the developments and discoveries 1 through 7
above being in the public domain, it essentially meant that any country with sufficient money
and expertise could eventually make an atomic bomb. The amazing thing about the Manhattan
Project was that they were the pioneers, and made the bomb in just 5 years- an enormously
significant achievement for someone doing it for the first time in the world. :)
Updated 16 Sep, 2011. 3,869 views.
Downvote
Comments1+
Graeme Shimmin, amateur military historian.
9 upvotes by Jay Wacker (physicist, phd+postdoc+faculty), Quora User, Quora User, (more)
The role of the Einstein-Szillard letter in precipitating the Manhattan Project is greatly
exaggerated. The Einstein-Szillard memo was written in 1939, the Manhattan project did not
start until 1941.
The letter resulted in the S-1 Uranium Committee, which did very little and had a tiny
budget. This was partly due to the fact that their understanding was that tons of Uranium 235
would be required, and hence the project was not very practical.
In 1940, the British (in fact Otto Frisch and Rudolf Peierls working for the British) correctly
appreciated that the amount of Uranium 235 required was far less than previously thought
(pounds rather than tons).
In late 1940, the British MAUD committee produced a report outlining the feasibility of the
bomb, which was sent to the Americans but ignored. The British started their "Tube Alloys"
project but couldn't afford to prioritize it as they were fighting for their lives.
The key event was the visit of Mark Oliphant of the MAUD committee to the USA in 1941,
where he impressed on the US scientists the feasibility and urgency of manufacturing the
bomb. After these meetings, in December 1941 Vannevar Bush created the Office of Scientific
Research and Development, after that the Manhattan Project took off and quickly eclipsed the

10. British project, which was eventually (1943) folded into it.
Some Wikipedia References:
http://en.wikipedia.org/wiki/Ein...
http://en.wikipedia.org/wiki/S-1...
http://en.wikipedia.org/wiki/Fri...
http://en.wikipedia.org/wiki/MAU...
http://en.wikipedia.org/wiki/Tub...
Richard Rhodes The Making of The Atomic Bomb covers this, along with the history of the
production of the Atomic Bomb, in great detail.
Updated 16 Sep, 2011. 1,622 views.
Downvote
Comments1+
James Aldridge, Ph.D. in animal physiology
5 upvotes by TJ Evans, Mousa Akkar, Mike Rayzman, (more)
Odd that Robert Oppenheimer's name doesn't appear yet. He was the master conductor of the
grand orchestra that was the Manhattan Project. If any one name deserves to be attached to this
invention, his does.
We don't give credit for a fine painting to the makers of its paints and canvas.
Oppenheimer was an artist in thought and in deed. We may certainly question the wisdom of the
bomb's development, as Oppenheimer himself did, but the inventor's name? No. No question:
Oppie.
Written 9 Feb, 2011. 1,098 views.
Downvote
Comments2
Eugene Miya, Retired.
2 upvotes by Quora User and Joseph Boyle.
I had two classes on the history of this topic and as such met and know a few of the survivors.
For a single point name Oppenheimer
is as good as any. He died some years before I took my classes, but I met and
spoke with his brother Frank at SF's exploratium when Frank was still alive (also Phil Morrison
when he was there). Another friend had a dad who was also at Los Alamos, and his name was

11. placed on the patent for the bomb (the implosion device) for the University of California (he
would go on to teach and run a different college after the war but fewer people except in physics
know his name).
Also don't forget there wasn't a single atomic bomb. From various ideas, 3-4 design directions
were explored (slightly askew of simultaneously) with a couple rejected and finally 2
mechanisms settled during the war and other design questions following the war (don't think they
stopped at these two, and not just for fusion and enhanced radiation). This is a fallacy by people
with only reading information.
Oppenheimer spent $2 billion which was about 10% of the entire US war effort. General Groves
had hoped to command a Division, the other 90% of the money went to 90 US Divisions, the
Marines, the Navy, and helping all Allies. General Groves could not complain.
Updated 20 Mar, 2013. 873 views.
Downvote
Comment
Gwydion Madawc Williams, independent thinker and retired compu... (more)
1 upvote by Sudhendu Pandey.
No one person can be credited.
H G Wells had the concept worked out in 1914, based on the discovery of radiation.
Leó Szilard had the idea of a Chain Reaction, which made it feasible.
Actual development was done by an enormous team of scientists and engineers at the Manhattan
Project. Two distinct types of device were made, one based on uranium and the other on
plutonium.
See History of nuclear weapons at the Wiki for more details.
Written 20 Jul, 2013. 548 views.
Downvote
Comment
Michael Grainger
1 upvote by Jay Wacker (physicist, phd+postdoc+faculty).

12. Roosevelt. He permitted the Manhattan project to come into existence and allowed large amounts
of US economic resource to be diverted into the project. In my mind Oppenheimer and Groves
were merely functionaries, and both were treated as such. As to whether Roosevelt could be
called the inventor is perhaps not clear. If anything the inventors of the Atomic weapon were the
European scientists who worked in this area in the early part of the 20th century.
You could argue that what the US had was the economic resource to facilitate the horrendously
expensive task of isotopic separation in a nation which was not subject to either aerial
bombardment or enemy action.
Written 9 Sep, 2014. 530 views.
Downvote
Comments2+
Quora User, Four semesters of Physics! Passed all... (more)
1 upvote by Uri Tsubu.
Depends what you mean by "invent". As soon as radioactivity was discovered, and the energy
density was calculated, anybody could see that if you could release the energy seen in radioactive
decay more quickly, you could get a lot of energy out. If you released it REALLY quickly,
you'd have a bomb. I think it was Leo Szilard who thought of the concept of a chain
reaction. He probably could have patented that.
The folks that actually did it were thousands of scientists and engineers that figured out how to
extract U235 and make Plutonium and figured out how to make the first gun-type bomb and a bit
later the implosion bomb type.
Written 8 Feb, 2014. 411 views.
Downvote
Comment
Originally answered on
Who invented the atomic bomb?
Joe Harkins, Singer Actor Web Site Developer and Host
define "invent" please. You may as well ask who makes a film or who was your teacher. The A-
bomb project (AKA "The Manhattan Project") cost more than 2 Billion Dollars. At that time,
even just one billion was a lot of money (OK - today that would be like 200 Billion).
Written 21 Jul, 2013. 349 views.
Did you find this answer helpful? Yes • No

13. Comment
Godden Tommy
1 upvote by Kelly La Rue.
Robert Oppenheimer should be one of the ones
Written 10 Feb, 2011. 308 views.
Downvote
Comment
Matt Gattis, Watch a lot of History Channel, studi... (more)
2 upvotes by Paul Eccles and Quora User.
Many people were involved. It was known as the Manhattan Project.
Written 23 Jun, 2010. 315 views.
Downvote
Comment1
3 Answers Collapsed
Write an answer
Related Questions

How was the hydrogen bomb invented?

Which causes more damage, an atom bomb or a hydrogen bomb?

What was the mood at Caltech and MIT when the atomic bombs dropped on Japan?

How is an atomic bomb made?


14. What parts of China did MacArthur want to atom bomb? Did the US public know or
support this plan?

Nuclear Physics: How does an atomic bomb work?

How can I make an atom bomb?

How is it that Robert Oppenheimer, who was so greatly inspired by the Bhagvad Gita,
invented something so destructive like an atom bomb?

What was Einstein's contribution to the first atomic bomb?

What is the difference between an atomic bomb and a hydrogen bomb?

Were firebombing and other conventional bombing techniques more destructive for Japan
than the atomic bombs?

What is the most high-destruction causing weapon used officially by the military that's
not the atom bomb?

Hydrogen bomb, nuclear bomb, and atom bomb; what's the difference?

Can a terrorist easily make an atomic bomb provided access to Uranium?

How did Indians manage to build an atomic bomb?

15. 
What were the pros and cons of the United States dropping atomic bombs on Japan?

What would the world be like today if the atomic bomb was never invented?
search...
 Home
 Bios
 Styles
 Literature
 Research Centre
 Connect
 Contact us
 Introduction
 Learning Styles
 Teaching Styles
 Communication Styles
Learning Styles Menu
 Bloom, Benjamin
 Dunn, Kenneth & Rita
 Felder, Richard
 Gagné, Robert
 Gardner, Howard
 Kohlberg, Lawrence
 Kolb, David A.
 Piaget, Jean
 Vygotsky, Lev
Translate this Page
Partcipant Pool
Interested in Participating in Our New Research?
Find Out How You Can Be Part of our New Research Projects

16. Get Connected
ICELS.ca Blog
Robert Gagne’s Five Categories of Learning Outcomes and the Nine Events of Instruction
 Description,
 Main Elements,
 Table of the 9 Events of Instruction,
 References
Robert Gagné’s seminal work is his conditions of learning theory. It includes five categories of
learning outcomes and the nine events of instruction. Together, these two themes of Gagné’s
learning theory provide a framework for learning conditions.
Gagné’s work (1985) focuses on intentional or purposeful learning, which is the type of learning
that occurs in school or specific training programs. He believed that events in the environment
influence the learning process. His theory identifies the general types of human capabilities that
are learned. These capabilities are the behavioral changes (learning outcomes) in a learner that a
learning theory must explain. Once the learning outcomes are identified, an analysis of the
conditions that govern learning and remembering can occur (Gagné, 1985, p. 15).
For example, a learner who is participating in a situation where the right conditions for learning
are invoked, then he or she will experience the five categories of learning outcomes that include
the human capabilities of intellectual skills, verbal information, cognitive strategies, motor skills,
and attitudes.
Gagné also relates learning outcomes to the events of instruction. He provides systematic
statements of theory to describe the ways that instructional events are designed for each of the
learning outcomes or capabilities.
While Benjamin Bloom (1956) developed his taxonomy of cognitive outcomes based on
increasingly complex levels, Gagné (1985) developed his five categories of learning outcomes
based on the characteristics of the content that a learner must learn. His outcomes do not consist
of any particular order or complexity of levels, other than the sub-categories within the
Intellectual Skills category. Gagné separated Bloom’s knowledge class into a category he named
verbal information, and he added another category of learning outcomes he named cognitive
strategies. He believed cognitive strategies were learning strategies that learners adopted and
applied in the process of learning, and that they are not subject specific (Wager, n.d.).
Description of Gagné’s Conditions of Learning Theory
Gagné’s conditions of learning theory draws upon general concepts from various learning
theories in order to define what learning is. The theory looks at the observable changes in human
behaviour that confirm that learning has occurred. Gagné’s theory provides an answer to the
question, “what is learning?” In answering that question, Gagné provides a description of the
conditions under which learning takes place by referring to situations in ordinary life and in

17. school where learning occurs, and by referring to experimental studies in learning.
Gagné (1985) postulates that proof of learning shows by a difference in a learner’s performance
before and after participating in a learning situation. He claims that the presence of the
performance does not make it possible to conclude that learning has occurred; but instead, it is
necessary to show that there has been a change in performance. In other words, the capability for
exhibiting the performance before learning requires consideration as well as the capability that
exists after learning (p. 16).
The following four elements provide the framework for Gagné’s Conditions of learning theory.
 Conditions of Learning
 Association Learning
 The Five Categories of Learning Outcomes
 The Nine Events of Instruction
Conditions of Learning
Gagné (1985) describes two different types of conditions that exist in learning: internal and
external. Capabilities that already exist in a learner before any new learning begins make up the
internal conditions necessary for learning. These internal conditions are transformed during the
learning process. External conditions include different stimulus’s that exist outside the learner
such as the environment, the teacher, and the learning situation. This means that each new
learning situation begins from a different point of prior learning and will consist of a different
external situation, depending on the learner and on the learning environment. Therefore, the
useful prototypes of learning by association (described next) are delineated by internal and
external learning conditions (p. 17).
Association Learning
There are three basic prototypes of learning that demonstrate the characteristics of associative
learning: classical conditioning, operant conditioning, and verbal association. Gagné adds a
fourth that relates to the three prototypes: chaining. Classical conditioning is the process where
the learner associates an already available response with a new stimulus or signal. Operant
conditioning is the process where a response in a learner is instrumental and thereby leads to a
subsequent reinforcing event. Verbal association occurs when the learner makes verbal responses
to stimuli that are words or pairs of words. Chaining is a process where a learner connects
individual associations in sequence. For example, a learner can recite verbal sequences
consisting of lists of words, or the alphabet from A-Z (Gagné, p. 24).
Gagné (1985) believes these four prototypes of associative learning are components of learned
human capabilities and link together as basic forms of learning (pp. 17-18). Gagné refers to them
so he may present a comprehensive picture of how these prototypes of learning relates to the five
categories of learning outcomes.
The Five Categories of Learning Outcomes
One of the themes of Gagné’s theory is distinguishing the types of outcomes that learning has:
the categories of learned capabilities - observed as human performances - that have common

18. characteristics. Gagné describes five categories of human performance established by learning:
 Intellectual skills (“knowing how” or having procedural knowledge)
 Verbal information (being able to state ideas, “knowing that”, or having declarative
knowledge)
 Cognitive strategies (having certain techniques of thinking, ways of analyzing problems,
and having approaches to solving problems)
 Motor skills (executing movements in a number of organized motor acts such as playing
sports or driving a car)
 Attitudes (mental states that influence the choices of personal actions)
The five categories of learning outcomes provide the foundation for describing how the
conditions of learning apply to each category.
Gagné (1985) postulates that if the five categories of learning outcomes and the ways of
analyzing learning requirements are combined in a rational and systematic manner, then it will
be possible to describe a set of ideas that make up a theory of instruction (p. 243). He adds that a
theory of instruction should attempt to relate the external events of instruction to the outcomes of
learning by showing how these events lead to appropriate support or enhancement of internal
learning processes (p. 244).
The Nine Events of Instruction
The events of instruction are the external events that help learning occur, and are designed to
achieve each of the five different learning outcomes. Gagné numbers the instructional events
from one to nine, showing a sequential order.
The nine events are as follows:
 Gaining Attention
 Informing Learners of the Objective
 Stimulating Recall of Prior Learning
 Presenting the Stimulus
 Providing Learning Guidance
 Eliciting Performance
 Providing Feedback
 Assessing Performance
 Enhancing Retention and Transfer
A summary of each of the nine events of instruction is in the Main Elements of Gagné’s
Learning Theory section of this page.
Together, the conditions of learning, association learning, the five categories of learning
outcomes, and the nine events of instruction provide a description of the framework for Gagné’s
conditions of learning theory. The next section of this page provides detail of the five categories
of learning outcomes and the nine events of instruction.

19. Main Elements of Gagné’s Conditions of Learning Theory
The Five Categories of Learning Outcomes
In his theory, Gagné (1985) describes five categories of human performance established by
learning (learning outcomes): intellectual skills, verbal information, cognitive strategies, motor
skills, and attitudes. They are comprehensive and do not follow any specific order. Any learned
capability will have the characteristics of one or another of these categories.
The links below will take you to a brief summary of each of the five categories, summarized
from Gagné & Driscoll (1988) Essentials of Learning for Instruction (pp. 44-59).
 Intellectual Skills
 Verbal Information
 Cognitive Strategies
 Motor Skills
 Attitudes
Intellectual Skills
Intellectual skills involve the use of symbols such as numbers and language to interact with the
environment. They involve knowing how to do something rather than knowing that about
something. Intellectual skills require an ability to carry out actions. Often they require the
interactions with the environment through symbols such as letters, numbers, words, or diagrams.
When a learner has learned an intellectual skill, he or she will be able to demonstrate its
application to at least one particular instance of the subject matter learned.
Out of the five categories, intellectual skills is the only category that is divided into sub-
categories. The division is according to the complexity of the skill level, and how they relate to
each other. The more complex skills require the prior learning or mastery of the simpler skills
before the learning process is complete. The links below will take you to a brief summary of the
five sub-categories of intellectual skills.
 Discriminations
 Concrete Concepts
 Defined Concepts
 Rules
 Higher-Order Rules
Discriminations
Discriminations is the first skill to master in intellectual skills. It is the ability to distinguish one
feature of an object or symbol from another such as textures, letters, numbers, shapes, and
sounds. The human performance or learning outcome achieved by discrimination is the ability to
tell the difference among various stimuli. It is the prerequisite to further learning.
Concrete Concepts
Concept learning occurs after discriminations learning is complete. Concrete concepts are the
simplest of the two concept types and consist of classes of object features, objects, and events.

20. Some are relational such as up, down, far, near, higher, lower. The performance or learning
outcome achieved from mastery of concrete concepts is the ability to identify a class of objects,
object qualities, or relations by pointing out one or more examples or instances of the class.
Defined Concepts
Concepts not only require identification, but also definition. Defined concepts require a learner
to define both general and relational concepts by providing instances of a concept to show its
definition. For example, if a learner were to explain the concept alliteration, he or she must
define alliteration, and then be able to identify the components of alliteration, such as consonant
sound, beginning, sentence, etc., and then be able to provide specific examples of alliteration.
Rules
Once concepts are learned, the next sub-category of intellectual skills is rules. A rule is a learned
capability of the learner, by making it possible for the learner to do something rather than just
stating something. For example, when a learner learns the rule for forming an adverb to modify
an adjective, he or she knows that ly must be added to the modifier. Because a learner knows the
rule to add ly, he or she can apply it to an entire class of words instead of learning an adverbial
form for every adjective in the language, enabling the learner to respond correctly to words he or
she has never seen before. Rules make it possible to respond to a class of things with a class of
performances.
Higher-Order Rules
Higher-order rules are the process of combining rules by learning into more complex rules used
in problem solving. When attempting to solve a problem, a learner may put two or more rules
together from different content in order to form a higher-order rule that solves the problem. A
higher-order rule differs in complexity from the basic rules that compose it.
Problem solving using higher-order rules occurs in writing paragraphs, speaking a foreign
language, using scientific principles, and applying laws to situations of social or economic
conflict.
Verbal Information
Another category of learning outcomes is verbal information. This refers to the organized bodies
of knowledge that we acquire. They may be classified as names, facts, principles, and
generalizations. Verbal information is referred to as declarative knowledge, or knowing that.
The performance or learning outcome achieved through verbal information is the ability of being
able to state in a meaningful sentence what was learned. Some examples of acquired verbal
information are the ability to define Piaget’s stages of cognitive development; or, stating the
rules for scoring in a tennis match.
Cognitive Strategies
Cognitive strategies refer to the process that learners guide their learning, remembering, and
thinking. Where intellectual skills are oriented toward aspects of the environment by dealing
with numbers, words, and symbols that are external, cognitive strategies govern our processes of
dealing with the environment by influencing internal processes. A learner uses cognitive

21. strategies in thinking about what was learned and in solving problems. They are the ways a
learner manages the processes of learning, remembering, and thinking.
The performance or learning outcome achieved through cognitive strategies is having the ability
to create something new such as creating an efficient system for cataloging computer discs.
Motor Skills
Motor skills are the precise, smooth, and accurately timed execution of movements involving the
use of muscles. They are a distinct type of learning outcome and necessary to the understanding
of the range of possible human performances. Learning situations that involve motor skills are
learning to write, playing a musical instrument, playing sports, and driving a car. The timing and
smoothness of executing motor skills indicates that these performances have a high degree of
internal organization.
Attitudes
Another distinct category of learning outcomes is attitudes, the internal state that influences the
choices of personal actions made by an individual towards some class of things, persons, or
events. Choices of action (behaviours) made by individuals are influenced significantly by
attitudes. For example, an attitude towards the disposal of trash will influence how a person
disposes of pop cans, food containers, organics, etc. An attitude towards music will influence the
choice of music an individual will listen to.
General classes of attitudes include attitudes that affect social interactions, attitudes that consist
of positive preferences towards certain activities, and attitudes that pertain to citizenship, such as
a love of country or showing concern for social needs and goals.
The performance or learning outcome achieved through attitudes is evident in an individual’s
choice of actions. For example, choosing swimming over running as a preferred exercise, or
choosing not to participate in group events reflects how attitude motivates choices.
Table of the 9 Events of Instruction
Internal Process Instructional Event Action Example
Reception 1. Gaining Attention Use abrupt stimulus change
Expectancy
2. Informing learners of the
objective
Tell learners what they will be able to do
after learning
Retrieval to Working
Memory
3. Stimulating recall of prior
knowledge
Ask for recall of previously learned
knowledge or skills
Selective Perception 4. Presenting the stimulus Display the content with distinctive features
Semantic Encoding 5. Providing learning guidance Suggest a meaningful organization
Responding 6. Eliciting performance Ask learner to perform
Reinforcement 7. Providing feedback Give informative feedback

22. Retrieval and
Reinforcement
8. Assessing performance
Require additional learner performance, with
feedback
Retrieval and
Generalization
9. Enhancing retention and
transfer
Provide varied practice and spaced reviews
Gaining Attention
The first event of instruction is to gain the attention of students so they are alert for the reception
of stimuli. An instructor can achieve this by introducing a rapid stimulus change either by
gesturing or by suddenly changing the tone or volume of their voice. Another way of stimulating
alertness is by visual or auditory stimuli related to the subject matter. The stimulus chosen for
gaining attention will work equally well for all categories of learning outcomes.
Informing Learners of the Objective
The second event of instruction is to inform the learner of the purpose and expected outcomes of
the learning material. This will provide them with an expectancy that will persist during the time
learning is taking place. Feedback at the end of the lesson will provide the learner with
confirmation of learning.
An important part of this event of instruction is to provide learners with motivation if learner
motivation is not apparent. An instructor can achieve learner motivation by relating an
interesting career field to the learning material.
Instructional techniques that will inform the learner of objectives for all five categories of
learning outcomes are described below.
 Intellectual Skills: Instructors can demonstrate the activity to which the concept, rule, or
procedure applies.
 Cognitive Strategy: Instructor describes or demonstrates the strategy
 Verbal Information: Instructor describes what the learner will be expected to state.
 Attitude: The learner encounters attitude later in the process. (This occurs through
instructor demonstration or modeling during instructional event five, providing learning
guidance.
 Motor Skills: Instructor demonstrates the expected performance.
Stimulating Recall of Prior Learning
The third event of instruction asks the instructor to recall skills or knowledge learners have
previously learned. The best kind of recall should naturally relate to the subject matter being
learned. The instructional technique for stimulating recall will be different for the different
learning outcomes as described below.
 Intellectual Skills: Instructor recalls prerequisite rules and concepts
 Cognitive Strategy: Instructor recalls simple prerequisite rules and concepts
 Verbal Information: Instructor recalls well organized bodies of knowledge
 Attitude: Instructor recalls a situation and action involved in personal choice. He or she
reminds learner of the human model and model’s characteristics.
 Motor Skills: Instructor recalls the “executive subroutine” (the procedure that constitutes

23. the active framework within which the motor skill is executed, practiced, and refined),
and part-skills (the different parts of the procedure), if appropriate.
Presenting the Stimulus
The fourth event of instruction is presenting a stimulus that is related to the subject matter. The
content of the stimulus should be specific to the learning outcome. For example, if the stimulus is
verbal information, printed prose such as a chapter in a textbook or an audio tape will achieve the
learning objective. If the stimulus is an intellectual skill, the instructor can display the object
and/or symbols that require a concept or rule; or, he or she can present the problem learners need
to solve.
The instructor must present the stimulus as an initial phase of learning, so clear indication of
stimulus features such as underlining, bold print, highlighting, pointing, or using a change in tone
of voice to emphasize major themes is helpful.
The instructional techniques for presenting the stimulus to different learning outcomes are as
follows:
 Intellectual Skills: Instructor delineates features or the objects and symbols that require
defining as a concept or a rule
 Cognitive Strategies: Instructor describes the problem and shows what the strategy
accomplishes
 Verbal Information: Instructor displays text or audio statements, showing or highlighting
the distinctive features
 Motor Skills: instructor displays the situation at the initiation of the skilled performance,
and then demonstrates the procedure
 Attitude: Instructor presents a human model that describes the general nature of the
choice that learners will be required to make.
Providing Learning Guidance
The fifth event of instruction, providing learning guidance requires the instructor to make the
stimulus as meaningful as possible. There are several ways to achieve this, depending upon the
learning outcome expected. An instructor can enhance meaningfulness by using concrete
examples of abstract terms and concepts, and elaborating ideas by relating them to others already
in memory.
The instructional techniques for providing learning guidance to different learning outcomes are
as follows:
 Intellectual Skills: Instructor provides varied concrete examples of the concept or rule
 Cognitive Strategies: Instructor provides a verbal description of the strategy, followed by
an example
 Verbal Information: Instructor elaborates content by relating to larger bodies of
knowledge; uses images and/or mnemonics
 Attitude: Instructor uses the human model and describes or demonstrates an action
choice, followed by observation of reinforcement of model’s behaviour

24.  Motor Skill: Continue practicing procedure, focusing on precision and accurately timed
execution of movements
Eliciting Performance
The sixth instructional event eliciting performance asks a learner to demonstrate the newly
learned capability. This may be verbal information, intellectual skills, cognitive strategy, attitude,
or motor skill. The learner of verbal information will have the ability to “tell it.” The learner of a
new concept or rule (intellectual skills) will have the ability to demonstrate its applicability to a
new situation not previously encountered during learning. The learner of a cognitive strategy of
problem solving will solve an unfamiliar problem whose solution may use the strategy. The
learner of a motor skill demonstrates the learned performance. The learner demonstrates the new
attitude in the choices the learner makes.
Providing Feedback
The seventh instructional event, providing feedback, asks the instructor to reinforce the newly
acquired learning. An instructor can accomplish this through informative feedback where the
instructor informs the learner of the degree of correctness or incorrectness of the performance.
This feedback may be verbal or written.
Assessing Performance
The eighth instructional event, assessing performance, consists of assessments to verify that
learning has occurred. In order to assure that learning is stable, an instructor will require
additional instances of the performance.
The instructor assesses performance through testing the learner. The purpose of testing is to
establish that the learned capacity is stable, and to provide additional practice to assist in
consolidating the learned material.
Enhancing Retention and Transfer
The ninth instructional event, enhancing retention and transfer, refers to retaining the learned
capability over a long period of time and transferring it into new situations outside of the
learning environment. Practice ensures retention, especially with verbal information, intellectual
skills, and motor skills.
Instructors can enhance retention and transfer by conducting spaced reviews. This means
conducting recalls of information learned at various intervals of a day or more after the initial
learning. However, the recall is further enhanced when additional examples are spaced in time
over days and weeks following the initial learning, and when including a variety of different
situations.
References
Bloom, B.S., Engelhart, M.D., Furst, E.J., Hill, W.H., & Krathwohl, D.R. (Eds.). (1956).
Taxonomy of Educational Objectives – The Classification of Educational Goals – Handbook 1:
Cognitive Domain. London, WI: Longmans, Green & Co. Ltd.

25. Gagné, R.M. (1985). The Conditions of Learning and Theory of Instruction (4th Edition). New
York: CBS College Publishing.
Gagné, R.M. & Driscoll, M.P. (1988). Essentials of Learning for Instruction (2nd Edition). New
Jersey: Prentice-Hall Inc.
Wager, W.D. (n.d.). Legacy of Robert M. Gagné. Retrieved from Florida State University
Department of Education on August 7, 2009 at: http://www.mailer.fsu.edu/~wwager/gagne.doc
Copyright © 2015 . All Rights Reserved.
Joomla! is Free Software released under the GNU/GPL License.