To me this just seems the wrong way to approach scientific method with elementary children. Why not instead have the exeripmental plant be fed plant food?
Sundiver, correct me if I misunderstood, but as described, the experiment appears to be for the purpose of seeing what happens to healthy plants under two conditions:
1. when the plant's needs are met
2. when the plant's needs are not met.
and to demonstrate the use of the scientific method in conducting the experiment.
How does your suggestion: "
Why not instead have the exeripmental plant be fed plant food?[/b]" make any sense at all in this context?