SNC 1D
How Do Scientists Solve Problems?
Parts of an Experiment
1. Ask a ________________
Example:
2. Make a ____________________ – a suggested answer to your question. A hypothesis makes a good guess at how one variable might affect another. It is often written using an if-then statement.
Example:
3. Determine your variables.
Variable:
Three types of variables:
· Independent variable: the _________________ variable.
It is the one thing in the experiment that you purposely change.
Example:
· Dependent variable: the ___________________ variable
It is what you measure in your experiment. It depends on the variable that you purposely change (the independent variable).
Example:
· Controlled variables: Variables that are ______________ to change during an experiment. This keeps the experiment fair.
Examples:
Note: Where does your independent variable appear in your hypothesis?
Where does your dependent variable appear in your hypothesis?
4. Gather ____________________
5. Design a _________________________ and carry it out.
6. Record your ___________________________. Observations may be:
a. Qualitative – describes how an object looks, feels, smells, etc. without using numbers.
Examples:
b. Quantitative – describes an object using numbers and units (measurements). These observations are often given in chart form.
Examples:
7. Discuss the observations – explain what they mean.
8. Conclude your findings.
How Do Scientists Solve Problems? THEY DO EXPERIMENTS!!!
Parts of an Experiment
1. Ask a question
Example: Does the cost of a battery affect how long the battery will last?
2. Make a hypothesis – a suggested answer to your question. A hypothesis makes a good guess at how one variable might affect another. It is often written using an if-then statement.
Example: If the battery costs more money, then the battery will last longer.
3. Determine your variables.
Variable: something that can change in an investigation.
Three types of variables:
· Independent variable: the CAUSE variable.
It is the one thing in the experiment that you purposely change.
Example: cost of the battery
· Dependent variable: the EFFECT variable
It is what you measure in your experiment. It depends on the variable that you purposely change (the independent variable)
Example: length of time the battery lasts
· Controlled variables: Variables that are NOT allowed to change during an experiment. This keeps the experiment fair.
Examples: Same machine used to test batteries
Batteries are the same size
Batteries are all brand new
Note: Where does your independent variable appear in your hypothesis?
Where does your dependent variable appear in your hypothesis?
4. Gather materials
5. Design a procedure and carry it out
6. Record your observations. Observations may be:
a. Qualitative – describes how an object looks, feels, smells, etc. without using numbers
Examples:
b. Quantitiative – describes an object using numbers and units (measurements). These observations are often given in chart form.
Examples:
7. Discuss the observations – explain what they mean.
8. Conclude your findings.
Practice with Variables Use another piece of paper to write down your answers.
A. For each problem below, write a hypothesis using an if-then statement, and then identify the three types of variables.
1. Does the distance you stretch an elastic band affect the distance it will fly when released?
Hypothesis:
Independent variable (IV):
Dependent variable (DV):
Two control variables (2 CV):
2. Does the amount of watering affect the number of flowers on geranium plants?
Hypothesis:
IV: 2 CV:
DV:
B. For each experiment below, identify the independent variable, the dependent variable and all the controlled variables.
1. A student wanted to test the cleaning power of four different detergents. She poured 5 mL of each into 5 equally greasy dishes, and then wiped them with a sponge and then rinsed with water. Then she looked at the amount of grease that was left on each.
2. Some famous pond ecologists were studying zebra mussels and their effect on ponds around Baden. They found two ponds that were similar in shape, size, and sunlight amount, and then counted the fish in both. Then they added zebra mussels to Pond A, but not to Pond B. One month later, they returned, and again, counted the number of fish in each.
3. Bill and Sue were arguing about the best type of cassette tape on which to tape their favourite rock music. They purchased three different types of cassette tape –Maxell, TDK, and Sony – and taped their favourite song on each of the tapes, and then listened to the tapes.
4. Oscar and Cassandra wondered whether tennis balls bounce differently when wet. They took two brand-new Wilson tennis balls. One they soaked in water, and the other they kept dry. They released both balls from 1 meter off the floor and then measured the height of the first bounce.
C. Alice wants to know whether mold grows better in warm or cool conditions. Describe how she could perform an experiment to answer this question. Then, identify the independent variable, dependent variable, and three controlled variables.