im lorraine, and a 16 years old 2ndyr electronics engineering student, we need to have or i mean we are required to present a project proposal, simple but useful. affordable and efficient. thanks sir. Need some help. God bless

 

here is a schematic for a logic probe. it is a buzzer to sound the signal instead of an LED. http://www.electronic-project-circuit.com/logic-probe-tester-with-audio/
or you could do a search for an air ionizer circuit. this circuit modifies the ions in the air in your room...

 

I'd say something that's easily demonstrated would be best.

Depending on how much you know, a solar tracker circuit could be neat.