Science Buddies: "Ask an Expert"

How does nitrogen affects plant growth experiment? Please give the purpose, hypothesis, possible materials, and three resources would be very much appreciated. I do not understand the meaning of a "control" in this experiment as there needs to be 3 plants: one with nitrogen, one without nitrogen, and the control. Please inform me what I should do for the control plant (like how much nitrogen or things should I add to that one).

Moderator note: https://www.sciencebuddies.org/science- ... ant-growth

Hello, the link provided has the objective, which is to compare plant growth with and without nitrogen. From this, you should write the hypothesis out. There are a few ways to do this, one common one being the "If... then..." statement.

The materials list is provided:

• At least eight small pots
  Potting soil
  One packet of seeds
  Commercial nitrogen fertilizer mix for house plants (e.g., Miracle Gro, Peter's or equivalent)
  Empty glass or plastic bottle for mixing nitrogen fertilizer

The link also has some resources for further reading.

A control is the group that is somewhat of a baseline. You will have your independent and dependent variables and the control will be unaffected by the dependent variable. This also ties back to your hypothesis.

There will total be at least 8 plants, as you want replicates in order for statistical power. There will be 4 control plants and 4 experimental plants. The link provided should help you get started.

Hello!
In addition to the excellent suggestions by the previous expert, here's a link to a Science Buddies article about "variables", which describes what a control variable is:

https://www.sciencebuddies.org/science- ... /variables

Good luck with your science project!
Madeline