Question

I am doing a project in 7th grade for science to do one of these things

Answer 1

I would obviously suggest choosing a topic where you feel most comfortable. 
However, I would recommend the bulletin board since all you have to include is size difference + information

Secondly, the scale. It really depends on the level of your artistic talent but it seems fun.

The let's bake a model is last since that would probably be the most challenging and time-consuming.

Hope this helped you make your decision! 

Answer 2

I would personally choose the lets bake a model