Clean out your change jar and make your very own penny-powered, desktop scale. This balancing device has its roots in ancient Egypt where balancing scales were first developed around 3000 BC. Those scales were used on oxen and were of little use in weighing small amounts however. As trade developed over the centuries, smaller scales for weighing quantities of precious metals and spices were invented.

The pennypower scale is similar to a postal scale and can weigh objects up to 1½ ounces. You could also build additional scales with different weight ranges simply by adding more pennies and adjusting the weight marks on the quadrant. This would be great for teaching kids differences in weight.