1. Hypothesis and Controlling Variables Lab
Part of the Scientific Process of Inquiry

2. She explains that yeast releases a gas as it feeds on sugar.
Problem/Question
John watches his grandmother bake bread. He ask his grandmother what makes the bread rise.
She explains that yeast releases a gas as it feeds on sugar.

3. Problem/Question
John wonders if the amount of sugar used in the recipe will affect the size of the bread loaf?

4. Caution! Be careful how you use effect and affect.
Effect is usually a noun. Affect is usually a verb.
“ The effect of sugar amounts on the rising of bread.”
“How does sugar affect the rising of bread?”

5. Observation/Research
John researches the areas of baking and fermentation and tries to come up with a way to test his question.
He keeps all of his information on this topic in a journal.

6. Formulate a Hypothesis
After talking with his teacher and conducting further research, he comes up with a hypothesis.
“If more sugar is added, then the bread will rise higher because sugar makes bread rise.”

7. Let’s learn about the 3 types of variables!
Hypothesis
The hypothesis is an educated guess about the relationship between the independent and dependent variables.
Let’s learn about the 3 types of variables!

8. The 3 types of variables!

9. Variable – any of the factors that could change in a Scientific Investigation. 3 Types of Variables
Independent Variable – something that is changed by the scientist
What is tested
Found after the word “if” in the hypothesis
The independent variable in John’s experiment is sugar.
John is going to use different amounts of sugar (25g., 50g., 100g., 250g., 500g. )in his experiment to see if the bread will rise higher with more sugar.

10. 3 Types of Variables
Dependent Variable: something that might be affected by the change in the independent variable
What is observed
What is measured to gather results
Is found after the word “then” in the hypothesis
The data collected during the investigation (graph, chart, etc.)
In John’s experiment, the dependent variable would be the size of the loaf of bread.

11. All experiments should have a control group.
3 Types of Variables
Controlled Variable: a variable that is not changed
Also called constants
Allows for a “fair test”
Control group: exposed to the same conditions as the experimental group, except for the variable being tested.
Serves as the standard of comparison.
The control group may be a “no treatment" or an “experimenter selected” group.
All experiments should have a control group.

12. Constants/Controlls
John keeps all other factors the same, except for the amount of sugar in each recipe, so that any observed changes in the bread can be attributed to the variation in the amount of sugar.
The constants would include: all the other ingredients to the bread recipe, oven used, rise time, brand of ingredients, cooking time, type of pan used, air temperature and humidity where the bread was rising, oven temperature, age of the yeast.

13. Identify the variables:
Hypothesis: If we add more air, then ball will bounce higher because the ball will be fuller.
Independent variable:
the amount of air in the ball
Dependent variable:
How high the ball bounces
Controlled variables:
type of ball, drop the ball from the same height, drop the ball on the same surface

14. Identify the variables:
Hypothesis: If a plant gets sunlight then it will grow because sunlight helps plants grow.
Independent variable:
sunlight
Dependent variable:
Growth of plants
Controlled variable:
Type of plant, pot, dirt, water, location, fertilizer

15. What did SpongeBob do wrong with this experiment?
Flower Power
SpongeBob loves to garden and want to grow lots of pink flowers for his pal Sandy. He bought a special fertilizer to see if it will help plants produce more flowers. He plants two plants of the same size in separate containers with the same amount of potting soil. He places one plant in a sunny window and waters it every day with fertilized water. He places the other plant on a shelf in a closet and waters it with plain water every other day.
What did SpongeBob do wrong with this experiment?

16. Flower Power Too many things are different!
In order to test the fertilizer correctly, both plants should have been placed in the sunny window and watered every day.
The only difference should be that one plant is watered with plain water and one plant is watered with the fertilizer water.

17. Controlling Variables Lab
Follow the directions on the lab sheet.
As you work, identify the variables in this lab.
Complete all questions on both sides of the lab sheet to hand in.
Write a lab report
together as a group,
Using the yellow
Butcher paper.
Use your green
sheet as a reference.
Be sure to have all
parts of the Scientific
Method on your lab
Write-up.