1. Experimental Design

2. Independent Variable the variable that is changed on purpose
the cause, stimulus, manipulated variable
This is the ‘’if” part of a hypothesis and is graphed on the “x” axis.

3. Dependent Variable the variable that responds
The effect(s), result(s), responding variable, etc.
This is the ‘’then” part of a hypothesis and is graphed on the “Y” axis.

4. The dependent variable can be:
Quantitative Data
Specific, numerical measurements
Use metric system units (cm, ml, gram, ◦C)
Qualitative Data
Descriptive, non- numerical
Ex: Color, shape, texture, smell

5. Constants Do not change (items to set up the lab)
Must have at least five constants always…..

6. Control Group contains NO variable, only constants
Dependent Variable results are compared to this group

7. the group(s) being tested contain the independent variable
Experimental Group
the group(s) being tested contain the independent variable
only one factor is changed

8. Repeated Trials
number of repetitions
Increases validity

9. to design an experiment.
The IVCDV chart
is used
to design an experiment.
Research:
Redi
Spallanzani
Pasteur

10. Alka Seltzer Lab

11. Does the amount of water affect Alka Seltzer?
Measure 100 ml of water (use beaker).
Determine the temperature of the water to the nearest tenth of a ºC.
Add one tablet. Determine the temperature at the end of the reaction.
Repeat, but this time use 50 ml of water.

12. The independent variable is changedIV
Constants DV
Amount of Water
The independent variable is changed

13. The measurable results …the dependent variable.IV
Constants DV
Temperature change
Amount of water
The measurable results …the dependent variable.

14. Factors that remain the same.IV
Constants DV
Amount of water
container
Temperature change
Amount of alka seltzer
Time
Factors that remain the same.
How fast

15. forming a
hypothesis

16. If the amount of water is increasediv
constants
container
Amount of alka seltzer
Time
Themometer
Light
Room Temeperature dv
Amount of water
Temperature change
+ verb
+ verb
If the amount of water is increased
then the change in temperature will decrease because……………….……………………………..

17. Hypothesis or claim of experiment
Must connect independent variable to dependent variable and justify the outcome.

18. Extension: What other factors could affect results?