1. designing an
experiment

2. A variable is something that changes.

3. 6 concepts of experimental design
independent variable
dependent variable
constants
control group
experimental group
repeated trials

4. the variable that is changed on purpose by the experimenter
independent variable
the variable that is changed on purpose by the experimenter
aka cause, stimulus, reason, manipulated variable, etc.
This is the ‘’if” part of a hypothesis.

5. the variable that responds
dependent variable
the variable that responds
aka effect(s), result(s), responding variable, etc.
This is the ‘’then” part of a hypothesis.

6. all factors which are NOT allowed to change during the experiment
constants
all factors which are NOT allowed to change during the experiment

7. the group (standard) to which everything is compared
control group
the group (standard) to which everything is compared

8. the group(s) being tested with the independent variable
experimental group
the group(s) being tested with the independent variable
Each test group has only one factor different from the other test groups: the independent variable.

9. the number of times the experiment is repeated
repeated trials
the number of times the experiment is repeated
The more times you repeat the experiment, the more VALID your results are.

10. is used to design an experiment.
IVCDV
The
chart
is used to design an experiment.

11. iv
constants dv
fertilizer
The variable (factor) that you will change is the independent variable.
0 drops
0 drops
0 drops
These are the fertilizer amounts varied by the experimenter.
2 drops
Plants with no fertilizer make up the control or control group.
4 drops
6 drops

12. iv
constants dv
fertilizer
plant growth
0 drops
2 drops
The variable (factor) resulting from the independent variable is the dependent variable.
4 drops
6 drops

13. iv
constants dv
fertilizer
amt. of water
plant growth
These are the factors that must NOT change during experimentation. They must remain constant.
type of soil
0 drops
amt. of soil
2 drops
type of plant
4 drops
type of planter
6 drops
size of planter
type of light
location

14. 6 drops fertilizer
4 drops fertilizer
2 drops fertilizer
no fertilizer

15. EXPERIMENTAL GROUP CONTROL 2 drops fertilizer 4 drops fertilizer
What is this called?
What are these called?
CONTROL
EXPERIMENTAL GROUP
no fertilizer

16. What are these called?
CONSTANTS

17. dependent variable What is this called?
The plant growth that you observe here can be called . . .
 the results (of adding fertilizer)
 the response (to adding fertilizer)
dependent variable
 the effects (of adding fertilizer) 2 4 6

18. Fertilizer becomes a constant. Type of soil becomes the IV.
What do you do if you want to test the type of soil instead of fertilizer?
amt. of water
type of plant
type of planter
size of planter
amt. of soil
type of light
location
type of soil iv
constants dv
fertilizer
type of soil
plant growth
fertilizer
Fertilizer becomes a constant.
Type of soil becomes the IV.

19. Take 7 minutes to design an experiment using the IVCDV chart to test the strengths of various sunscreen on aliens.
5 spf
10 spf
15 spf
20 spf

20. Evaluate the experimental design in the next two slides.

23. forming a
hypothesis

24. V Chart

25. If fertilizer is added to plants, then plant growth will improve.iv
constants
amt. of water
type of soil
type of plant
type of planter
size of planter
amt. of soil
type of light
location dv
fertilizer
plant growth
+ verb
+ verb
If fertilizer
is added to plants,
then plant growth
will improve.

26. If independent variable + verb, then dependent variable + verb.
V Chart
Independent Variable
Dependent Variable
+ verb
+ verb
If independent variable + verb,
then dependent variable + verb.
hypothesis

27. recording and displaying
results

28. iv
constants dv
fertilizer
plant growth
0 drops
Results from your experimentation should be recorded in a carefully constructed data table.
2 drops
4 drops
6 drops

29. A data table has at least 2 columns of information.iv
constants dv
fertilizer
plant growth
0 drops
1 cm
2 drops
1.5 cm
4 drops
1.5 cm
6 drops
3 cm
A data table has at least 2 columns of information.

30. IV fertilizer 0 drops 2 drops 4 drops 6 drops
Independent variable data is always (a) recorded in the left column (b) recorded BEFORE experimentation

31. fertilizer 0 drops 2 4 6 2 drops 4 drops 6 drops2 4 6
2 drops
4 drops
6 drops
Independent variable data is always (a) recorded in the left column (b) recorded BEFORE experimentation

32. DV plant growth 1 cm 2 4 6 1.5 cm 1.5 cm 3 cm
fertilizer (drops) DV
1 cm 2 4 6
1.5 cm
1.5 cm
3 cm
Dependent variable data is always (a) recorded in the right column (b) recorded DURING experimentation

33. plant growth
fertilizer (drops)
plant growth (cm)
1 cm 2 4 6 1
1.5 3
1.5 cm
1.5 cm
3 cm
Dependent variable data is always (a) recorded in the right column (b) recorded DURING experimentation

34. Choose an appropriate title for the data table.
Effect of Fertilizer on Plants
fertilizer (drops)
plant growth (cm) 2 4 6 1
1.5 3
Choose an appropriate title for the data table.

35. Effect of Fertilizer on Plants
fertilizer (drops) 2 4 6
plant growth (cm) 1
1.5 3
Effect of Fertilizer on Plants
Data from a correctly constructed data table can be displayed in a graph.

36. Effect of Fertilizer on Plants
fertilizer (drops) 2 4 6
plant growth (cm) 1
1.5 3
Effect of Fertilizer on Plants
1.0
2.0
1.5 .5
2.5
3.0
plant growth (cm) 2 4 6
fertilizer (drops)
IV data is plotted on the X axis DV data is plotted on the Y axis.

37. Effect of Fertilizer on Plants
fertilizer (drops) 2 4 6
plant growth (cm) 1
1.5 3
Effect of Fertilizer on Plants
Effect of Fertilizer on Plants
1.0
2.0
1.5 .5
2.5
3.0
plant growth (cm) 2 4 6
fertilizer (drops)
The title of the data table is also the title of the graph.