I'm pretty sure it is physical and mental development
Try meditation every night before bed. Breath in through your nose count to 4 and breath out through your mouth and count to 4,do this 5-10 times when ever you feel really stressed and before bed. I do this every night and it helps me hope it works for Heidi and her sister
The earths water supply is not affected from water pollution
You do it before a lab so as to prevent contamination of the materials. You might have things on your hands that might contaminate the experiment and the research. You do it after because you don't want to have things from your experiments on your hands because that can be extremely dangerous.
