1. Identifying
Variables

2. A variable is something that can change in a situation
A variable is something that can change in a situation. What are the variables in the following statements?

3. _______________________
The time it takes to run a kilometer depends on the amount of exercise a person gets.
_______________________
time to run a kilometer
amount of exercise

4. time needed for egg to cook
The higher the temperature of water, the faster the egg will cook.
_______________________
temperature of water
time needed for egg to cook

5. hours (amount) of light
An investigation was done to see if keeping the lights on for different amounts of time each day affected the number of chicken eggs layed.
_______________________________
hours (amount) of light
number of eggs

6. height of grass, amount of water and amount of fertilizer
Grass will grow taller if it is watered evenly and is fertilized.
_______________________
height of grass, amount of water
and amount of fertilizer

7. If a variable is deliberately changed in a situation, it is called ______________________________________________
manipulated variable
independent variable

8. What variable is being manipulated in the following situations?

9. amount of lead in gasoline
The amount of pollution produced by cars was measured for cars using gasoline containing different amounts of lead?
_______________________
amount of lead in gasoline

10. amount of lead in gasoline
The amount of pollution produced by cars was measured for cars using gasoline containing different amounts of lead?
_______________________
amount of lead in gasoline

11. Lemon trees receiving the most water produced the largest lemons.
_______________________
amount of water

12. # of sacks of phosphate fertilizer sold
The amount of algae growth in lakes seems to be directly related to the number of sacks of phosphorous fertilizer sold by local merchants.
_______________________
# of sacks of phosphate fertilizer sold

13. _______________________
An investigation was performed to see if corn seeds would sprout at different times depending on the temperature of the water in which they were placed.
_______________________
temperature of water

14. The variable that may change as a result of the manipulation is called the ______________________________________________
responding variable
dependent variable

15. Identify the manipulated (independent) variable & the responding (dependent) variable in the following situations.

16. # of bushels of potatoes
More bushels of potatoes will be produced if the soil is fertilized more.
MV (IV) ______________
RV (DV)______________
amount of fertilizer
# of bushels of potatoes

17. MV (IV) ______________ RV (DV)______________
5 groups of rats are fed identical diets except for the amount of Vitamin A that they receive. Each group gets a different amount. After 3 weeks on the diet, the rats are weighed to see if their weight has changed.
MV (IV) ______________
RV (DV)______________
amount of Vitamin A
weight of rats

18. minutes of spelling practice
An experiment was done with 6 groups of children to see if scores on their weekly spelling tests were affected by the number of minutes of spelling practice that they had each day.
MV (IV) ______________
RV (DV)______________
minutes of spelling practice
score on spelling test

19. distance from light to screen size of illuminated area
Students in a science class carried out an investigation in which a flashlight was pointed at a screen. They wished to find out if the distance from the light to the screen had any effect on the size of the illuminated area.
MV (IV) ______________
RV (DV)______________
distance from light to screen
size of illuminated area

20. MV (IV) ______________ RV (DV)______________
The State Agriculture Dept. has been counting the number of foxes in Brown County. Will the # of foxes have any effect on the rabbit population?
MV (IV) ______________
RV (DV)______________
# of foxes
# of rabbits

21. minutes of exposure to X-rays # of offspring born dead
A study was done with white rats to see if the number of offspring born dead was affected by the number of minutes of exposure to X-rays by the mother rats.
MV (IV) ______________
RV (DV)______________
minutes of exposure to X-rays
# of offspring born dead

22. Now! Let’s put the data from the variables into a table and learn how to graph the data.

23. Usually the manipulated variable (independent variable) is written on the left, but not always.
Length of Drop (cm)
Height of Bounce (cm) 10 8 30 24 50 40 70 56
100 80

24. The independent variable is always graphed on the
Length of Drop (cm)
Height of Bounce (cm) 10 8 30 24 50 40 70 56
100 80
X-axis

25. Y-axis X-axis X-axis Length of Drop (cm) Height of Bounce (cm) 10 8 3024 50 40 70 56
100 80
Y-axis
X-axis
X-axis

26. DEPENDENT
RESPONDING
AXIS
DRY
X-axis

27. MANIPULATED
INDEPENDENT
AXIS
MIX
X-axis