Do on the topic solar power first u prepare 2 charts in 1 chart ri8 about solar energy and in other chart write about the inventions of solar energy like all the collapse happened while constructing solar plants in google if u type solar energy u will get idea what is my idea is just with thermocol sheet make all trees and houses then in middle keep a pillar like and circuit light wil be know tthat one u TK and 2 wires will be to that nd then take battery and keep that battery down and when any one comes to see explain them by seeing in chart
Do a working system of lungs 
take a bottle cut the end of the bottle tie a ballon at the end of the bottle and inside the bottle take a straw fix it in the cap of the bottle in the straw fix another 2 straw and at the end tie a ballon in straw and close the cap of the bottle.remember the ballon at the bottom should be bigger than inside it .
after wards if u pull the ballon at the end the inside 2 ballon will expand thus from this experiment we can learn that as diaphragam expand lungs will take oxygen as it contract it gives co2