What is an “experiment”?• In school, “experiment” is often used to describe hands-on experiences
What actually is an“experiment”?• A science experiment tests a hypothesis
Components of anexperiment• Background research• Aim• Hypothesis• Equipment• Types of variables• Results• Discussion• Conclusion
Background research• Every experiment starts with a topic of interest (Eg. What are the effects of ocean acidification on living things?)• Background research finds out what we already know about the topic
Aim• Always starts with “To”• Tells the reader what the experiment aims to do• Eg. To find out how ocean acidification affects the shells of living things
Hypothesis• A prediction of the results based on the background research• Example – The more acidic the ocean is, the quicker the shells of ocean invertebrates will dissolveIf A happens then B will happen
Equipment and Method• List the equipment used in the experiment• Method lists how to do the experiment in steps• Always starts with a verb• Accompanied by a scientific diagram where appropriate
Types of variables• Independent variable – What we change on purpose (Eg. how acidic the water is)• Dependent variable – What we measure as the result (Eg. How much shells have dissolved after 3 days)• Controlled variables – What we keep the same to keep the experiment fair (Eg. The amount of acids and water; the type of shell; the temperature of the environment)• In most experiments there is ONE independent variable, ONE dependent variable and many controlled variables
Types of variables -Strategies• Cows Moo Softly – Change one thing – Measure one thing – Keep everything else the same
Controlled variables vs control3M HCl with 2M HCl with 1M HCl with Water withshell shell shell shell•Independent variable - concentration of acid•Dependent variable – how much each shell dissolves•Controlled variables – time of experiment, amount ofacid and water, type of shell•Control – the water with shell
Validity and reliability• Validity – Is the experiment testing what you intend to test?• Reliability – Are these results a fluke? If I repeated the experiment again, will I get the same results?
Replication• You shouldn’t just have one beaker of 3M acid, one beaker of 2M acid, etc.• You need 5 beakers of each acid so that there is replication.• Replication increases reliability.• You’ll need to use average calculations.
Results• A table and graph must be done• A graph shows patterns that cannot be seen easily in a table• It’s usually a choice between a column graph or a line graph• X-axis = independent variable• Y-axis = dependent variable
Discussion – analysis ofresults• What do the results mean?• Are the results expected? Are there any usual results?• What were some possible sources error?• How can the experiment be improved?• What are some other experiments to do in the future?
Conclusion• The aim written in past tense and says whether the hypothesis is correct• Eg. The effects of ocean acidification on shells were determined. The more acidic the water, the faster shells dissolve. The hypothesis was correct.