So after solat we get started, look for reference in you tube heheheheheh, well its true and its really helpfull.
Stuff we need , large plastic bag, straws, alluminium paper and small birthday candles.
Cut the alluminium paper and stick the candle on top , this is the best base for the candle, it avoid the melting wax dripping on the floor.
Attached the cross shape straws to each ends of the plastic .
As can be seen the burning candle heat up the air inside the plastic bag. So the boys saw how the hot air expand. However the plastic bag is too heavy, we cant get them to fly up.