1.  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.  Control – use the word “control”, but also indicated several variables that are being held constant.  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.

3.  Hypothesis – Say the word “hypothesis” and write in the “If….then…” format.  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.  Tell how the experiment is manipulated (i.e. what are your treatments). Give a full range of the treatment if possible to avoid the “Three Bears Syndrome” (one too hot, one too cold, one just right)  Ex – The plants will be grown in five treatments of differing temperatures from O o to 40 o in 10 degree intervals.

5.  Indicate to the reader what is being measured. Use quantitative measurements rather than qualitative.  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.  Use a large sample size (i.e. the “rule of 10X) or show that the experiment will be repeated several times.  Ex – There will be 10 plants in each treatment and control group.

7.  Tell the reader what you expect the results of the experiment to be and explain why.  Ex - The expected results of the experiment is that the plants with more light will have more photosynthesis, therefore, they should have more biomass.

8.  Labs don’t have to be exactly the way they were run in AP Bio, but they should be able to work.  Be sure to give the reader sufficient background on how the method works.  Use metric units.  Write clearly and with details.