Scientific Method Learning Target Study Guide Answers
1. Make quantitative and qualitative observations
Quantitative – there are two dogs on my porch
Qualitative – the dogs bark loudly
Quantitative – the cat has thrown up in three spots on the floor
Qualitative – the cat vomit is really stinky
2. Make Inferences from observations
Observation: the dog is standing and looking out the door. Her ears are alert,
she is barking
Inference: there is someone walking past the house
Observation: my sister is sweaty and wearing running clothes.
Inference: my sister has gone for a run
3. Write a hypothesis in if..then format
IF I do my study guide thoroughly, THEN I will do better on the test
IF the paper plane is light, THEN it will fly further
4. Write a testable hypothesis
(A testable hypothesis is one that includes an independent variable and a
dependable variable) IF the amount of carbon dioxide in the air increases,
THEN temperature will increase. In the example above, the first hypothesis is
not specific – how do you judge “better”? So is not really testable as written. To
make it more testable, it should read, IF I do my study guide, THEN my test
average will increase by 10 percentage points.
5. Differentiate between independent and dependent variables
An independent variable is what you are purposefully changing or measuring
in an experiment to see if it causes an effect on something else. For instance, in
the above example, you are measuring the amount of carbon dioxide to see if it
affects the temperature. A dependent variable is what is changing because of
the change in the independent variable – it DEPENDS on whatever the
independent variable is doing. If you are looking at the increase in
temperature, then that DEPENDED on the amount of carbon dioxide. In our
spatter lab, the size of the spatter DEPENDED on the height of the drop. The
height of the drop was the independent variable, it’s what you were
manipulating to see if it would cause an effect on something else. In our
airplane lab, the distance the plane flew was the dependent variable. The
independent variable is what you manipulated to affect the length of flight –
whether you made the plane heavier or used a different design, etc.
6. Identify the variables and controls in an experiment
The variables are what change; the independent and dependent variables. The
controls are everything else that stays the same in the experiment. In the
spatter lab, the Independent variable was the height of the drop. The
dependent variable was the size of the spatter. The controls were all the rest of
the procedures and equipment that you kept the same throughout all the trials
– the type of paper you dropped onto, the kind of paint, the consistency of
paint, the person doing the dropping, the tool you measured on, etc.
7. Explain the importance of controls in an experiment
Controls help make your experiment valid and reliable. If you changed which
partner in your spatter lab was doing the dropping, you may have changed the
velocity of the drop, or the force of the drop, which would have also affected the
size of the spatter. In the plane lab, if you changed throwers, you may also have
changed the angle of the throw, the speed of the throw, and then you’ve
introduced another variable.
8. Explain why having a single independent variable is important.
Say you actually conducted the experiment that was on your hypothesis
practice sheet and you decided to test whether giving your dog table scraps
instead of dry dog food would cause your dog to lose weight. You changed your
dog’s diet, and walked her more, and gave her a vitamin supplement. You then
weighed her after two weeks, and she did indeed weigh less. How do you know
which variable was the cause of the weight loss? Was it the walking or the
vitamins or the change to table scraps. Because you were not testing one single
variable, you don’t know what specifically caused the weight loss. But if you
changed her diet and she lost weight, you would know that the diet change is
what caused the weight loss. Testing one variable at a time allows you to be
more sure of your results
9. Collect data in an organized and properly labeled table/chart
A data table should be neat, have straight lines, have a title, and both columns
and rows should be labeled.
Distance in meters
Trail 1
Trial 2
Title
Airplane model 1
Airplane model 2
Airplane model 3
10. Identify and properly use common scientific equipment
In our class, a scale measures mass (weight), a graduated cylinder measures
volume, a meter stick or ruler measures length.
11. Use SI (metric) measurements
Mass is measured in grams
Length is measured in km, m, cm, or mm
Volume is measured in L or mm
12. Communicate the results of data collected in an experiment
The purpose of doing an experiment is to help solve a problem, and the world
needs all the information it can get. So once an experiment is complete, the
data needs to be shared with other scientists. Generally you would conclude
whether or not your hypothesis was supported by evidence, and then explain
what your findings were based on your data.
13. Explain why multiple trials of an experiment are necessary
Multiple trials lend validity to an experiment. When you did the spatter lab,
you may have dropped too much paint onto the sheet of paper. It’s only when
you look at multiple drops that you see if you’ve made any errors. Same with
the plane lab; if you only threw your plane once, it may have been taken by the
wind and gone quite far. But if that was your only trial, you would conclude
that the weight you added to the plane caused it to fly very far. However, if you
did multiple trials, you will have a larger sample size, which will be truer to
fact. If you only flipped a coin once, can you conclude that you will always get
tails? Multiple trials act as proof that your data set is a fair representation of
the experiment and that your results were not a fluke.