1. Design an Experiment Essay Questions
Many of the past National AP Biology lab based essay questions have asked students to “Design an experiment to…”
There are usually some common points in any question of this type. Here are some tips:

2. Common Points
Control – use the word “control”, but also indicate several variables that are being held constant ~controlled variables
ex – “plants of the same species, from the same seed source, grown in the same soil and under the same conditions”.
Be sure to indicate “which treatment” is serving as the control set up.

3. Common Points
Hypothesis – Say the word “hypothesis” and write in the “If….then…” format (weird… like a prediction, but not as specific.)
Example – The hypothesis for this experiment is if higher light allows more photosynthesis, then the plants with the most light should have the most mass.

4. Manipulation of the Variable
Tell how the experiment is manipulated (i.e. what are your treatments). Give a full range of the treatments if possible to AVOID THE “THREE BEARS SYNDROM”
(one too hot, one too cold, one just right)
ex. – “The plants will be grown in five treatments of differing temperatures from Oo to 40o in 10 degree intervals.”

5. Measurements
Indicate to the reader what is being measured. Use quantitative measurements rather than qualitative. USE UNITS!!
Tell when then measurements will be taken.
ex. – “The mass of the plants will be taken in grams at the beginning and end of the experiment”.

6. Verification
INDICATE you will use a large sample size (i.e. the “rule of 100X) or show that the experiment will be repeated several times.
ex. – “There will be 100 plants in each treatment and control group.”

7. Expected Results
Tell the reader what you expect the results of the experiment to be and explain why
GIVE THE SCIENCE BEHIND THE REASON.
ex. - “The expected results of the experiment are: the plants with more light will undergo more photosynthesis, creating more sugar, therefore, they should have more biomass.”