Hey There!
Here is your answer:
Your answer is that a experiments should be controlled because the experiment could go out of control which could harm or hurt someone.
Also the definition of a controlled experiment is a part of the experiment that's not touched.
Ex: Water is your controlled experiment that's because our not doing anything to the water.
If you need anymore help just ask me!
Hope this helps!
Answer: a tiny muscle connected to each hair follicle and the skin. When it contracts it causes the hair to stand erect, and a "goosebump" forms on the skin.
