Chapter 2 scientific investigations
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Chapter 2 scientific investigations

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Chapter 2 scientific investigations Chapter 2 scientific investigations Presentation Transcript

  • Chapter 2: SCIENTIFIC INVESTIGATIONS
  • WILL IT FLOAT OR SINK?
  • 1. descriptive Investigation
    : gather observational and measurement data to answer questions about the properties and actions of objects, organisms, events, and systems
    2. Classificatory Investigation
    : organize collected information by sorting and grouping it according to one or more properties in order to identify relationships and better define properties
  • Grandfather clock
    • What will change the speed of my pendulum in my grandfather clock so that I keep time correctly?
  • Experimental Investigation
    : conduct experiments, including controlled experiments, to determine how variables are related and to isolate causal factors in nature phenomena
  • hypothesizing – PP. 40-41
    • Hypothesis
    : a suggested explanation for a phenomenon (which is observable)
    : a reasoned proposal suggesting a possible correlation between multiple phenomena
    : a statement about a possible answer to a question that might be found through investigating
    • Informed by background knowledge, prior knowledge, experiences
    • Can be modified as inquiry progresses
  • Experiment (Variables) – PP. 41-42
    • Variables
    : something that can vary or change in a situation
    : something that can affect the outcome of the experiment
    • Manipulated Variables (independent V)
    : The variable which is purposefully changed in a situation
    • Responding Variables (dependent V)
    : The variable which may change or be affected as the result of the manipulation
    • Controlled Variables
    : The variable which are purposefully held constant or stable in a situation
  • Experiment (Trials)
    • How many times?
    • Multiple trials => averaged
  • Data collection and interpretation
    • Data table
    • Graphing (pp.36-38)
    : Pictorial representation of data
    => See some patterns or relationships
    • Line graph
    : Show changes in variables over time
    : Continuous variables (e.g. time, temperature)
    • Bar graph
    : Show differences in data
    : Numerical data related to categories - Discrete variables (e.g. the # of legs of an animal)
  • Data collection and interpretation
    • Histogram
    : the number of times a number even occurs in a large set
    : a graphical display of tabulated frequencies, shown as bars
    : shows what portion of cases fall into each of several categories
  • CONCLUSION
    • A statement which summarizes a set of observations made regarding some particular phenomenon
    • Your data support (accept) / do not support (reject)
  • How DOES my pendulum clock work?
  • pendulum
    • Something hanging from a fixed point which, when pulled back and released, is free to swing down by force of gravity and then out and up because of its inertia
    • Law of inertia
    : A body in motion will continue in motion, unless acted upon by a force
  • pendulum
    • Period
    : time for one swing of the pendulum over and back
    • Frequency
    : the number of back and forth swings in a certain length of time
  • Investigations
    M & M
  • Investigation with m & m
    From: Inquiry in Action (3rd ed.) by American Chemical Society
    • What happens when an M & M is placed in a plate of room-temperature water?
    Pour room-temperature water into a white plastic or foam plate so that it covers the bottom of the entire plate. Once the water has settled, place 1 M&M in the center of the plate. Be careful to keep the water and M&M as still as possible. Observe for about 1 minute.
    • Dissolving
    : Interaction between the molecules of the solvent (the liquid doing the dissolving) and the molecules of the solute (the substance being dissolved)
  • Investigation with m & m
    • Variables that will effect on the way M & M’s dissolve in water
    • Color of the M & M’s
    • The number of M & M’s
    • The temperature of water
    • Type of liquid & the concentration of the solution in which the M & M’s are placed
    • Questions you could investigate
    • Do some M & M colors dissolve in water faster than others?
    • What would the colors look like if we place two or more M & M’s in a plate of water?
    • Does the temperature of the water affect how fast the colored coating dissolves from an M & M?
    • Does the amount of sugar already dissolved in water affect how fast an M & M coating dissolves?
  • What happened? & Why?
    Because of the way oxygen and hydrogen atoms are bonded together, a water molecule has an area of positive charge and an area of negative charge. This makes the water a polar molecule. (The water molecule has no overall or “net” charge. It is neutral.)
    Because of water’s polarity, water molecules are attracted to each other.
  • What happened? & Why?
    Sugar (sucrose) also has oxygens and hydrogens bonded to each other. This gives sucrose many areas of positive and negative charge.
  • What happened? & Why?
    Water and sucrose are attracted to one another based on the attractions of opposite charges.
    When the attraction that water molecules have for sucrose overcomes the attraction sucrose molecules have for each other, the sucrose dissolves.
    The polar nature of water is what makes water so good at dissolving many substances.
  • HOW SMALL?
    The drawings and models of water molecules that you see or build are millions of times larger than the actual size of real water molecules. To get an idea of how small they are, consider this: Let’s say you had about a tablespoon of water and wanted to count all the water molecules in that amount of water. Assume you were a very fast counter and could count 1 million water molecules every second. Even at your very fast counting speed, it would take you over 190 million centuries to count all the water molecules in that small amount of water. WOW!