Question

What working model should I make for a science exhibition at my school. (Grade 7)

Answer 1

You can make a mechanical sieve by attaching a perforated paper (Make hole on a sheet of paper with the help of pins) to a square mould. Glue four wooden sticks together for a square, or use any other, if you have. Attach a small battery (available at any electrical store). You can show its working by using sand and bits of paper. The sand will be seperated from the paper.