The best way to introduce 'heavy' and 'light' is to choose a handful of objects and use your hands to feel which one is heavy and which is light! Have fun finding some objects from around the home or outdoor space to measure with!
If you fancy a challenge you could try making one of the DIY balancers below! You will need resources you may find at home such as; a coat hanger, wool or string, plastic cups, a shoebox lid , toilet roll and some glue! If you want to make something abit stronger you could use a plank of wood and dowel to balance and measure with.