You must keep careful records of all that you do and all that happens during your experiment. This should be in the form of a daily diary called a logbook..
Example:
1/13/99
Today I checked my plants at 5:30 P.M. I noticed that Group A seems to be growing faster than groups B, C, and D. Specifically, plant A2 seems to be growing the best. The plants in Group A aren't just taller, but seem to be greener and more healthy. It is interesting to note that the plant with the longest root development is plant C3. I don't know the reason for this. Here is a chart of my results for today:
| Plant | Height in cm. | # of Leaves | Root length in cm. | Observations |
| A1 | 5 | 4 | 3.1 | Has not grown |
| A2 | 5.2 | 5 | 3.4 | Has a new leaf |
| A3 | 5.3 | 4 | 3.4 | Is tallest in the group |
| B1 | 4.9 | 4 | 3.1 | Has not changed |
| B2 | 4.8 | 4 | 3.0 | Has not shown growth |
| B3 | 4.8 | 5 | 2.5 | Poor root growth |
| C1 | 5.0 | 4 | 2.3 | Poor root growth |
| C2 | 4.3 | 5 | 3.4 | Lowest height |
| C3 | 4.5 | 4 | 4.2 | Longest roots |
| D1 | 4.3 | 4 | 3.2 | Lowest height |
| D2 | 4.7 | 4 | 2.9 | Low root growth |
| D3 | 4.4 | 4 | 2.0 | Least root development |
