Global warming:take a cardboard and on it place a big plastic ball paint it as earth
then make a line from between and on left side show polluted earth and on right side show good earth 
cardboard par ek banner lagao and write"WHICH ONE DO YOU CHOOSE POLLUTED OR GOOD ONE???"

dude i gave u points draw toh u hv to do on own ...hope it helps thank button pe click kr do and mark as best answer