In order to measure the impact, we need to keep track of changes in our experiment.
This is the making observations/gathering data step of the experiment.
It also usually takes the longest, depending on your experiment.
When you make observations of your experiment you want to be sure to record any changes or differences that may have happened during your experiment.
When you observe, you should first review the notes you took previously, to help yourself detect any change.
You should also look carefully. Take your time and examine what the experiment looks like now.
Do not try to draw any conclusions about the experiment, just present an accurate representation of how it appears.