Balancing scales have been used throughout history, dating back between 2400 and 1800 B.C., when various sized stones were used as weights to balance different objects. In the 21st century, balance scales are a convenient way not only to teach children about weight and measurements, but a handy project that keeps learning interesting. Although balancing scale kits can be found in a variety of craft and hobby shops, you can also make your own, using only common household products.
Punch three holes each in both of the yogurt containers using the hole puncher, measuring approximately one-quarter of an inch below the rims. Insert a string or thread through each of the holes, then knot the ends tightly so that the strings will not slide through the holes. Keep in mind that other household containers will suffice and work just as well as yogurt containers, such as plastic margarine or butter bowls.
Tie the set of strings of one yogurt container to the left-hand end of a wire hanger, then tie the set of strings from the other yogurt container to the right-hand end of the hanger. Wrap duct tape around each set of strings so that the containers do not slide around on the hanger.
Create a set of weights with some pennies. Use a household measuring cup to measure different quantities, such as 7, 14 and 28 grams. Keep in mind that this will help you determine the weight of each object that you place in the measuring cups. Note that once you place the measuring cups on your new scale and they balance, they are the same weight.