How Do You Make A Balance Scale With Recycled Materials?

A balance scale is a simple and surprisingly accurate way to compare the weight of two things. It works just like a see-saw. If objects of equal weight are added to either side of a lever the same distance from the fulcrum, they will balance perfectly. Otherwise, the heavier one will pull its end down. Get a thin board, about 2 inches wide and 1 to 2 feet long. Find the center of gravity by balancing it on your finger. Hammer a long nail straight through the center of it. Cut off the bottoms of two soda bottles of equal size. You can cut off a small section of the bottom or a large one, as long as you cut off an equal piece from each bottle. Attach the bottle bottoms to each end of the wooden board so that both are facing up. You can use tape or glue, or simply nail each to the board. Cut the top off of a 2-liter bottle. Then, cut two grooves into it for the nail to rest in. Put some dirt or rocks in the bottom of the bottle to weigh it down and make it more stable. Rest the nail in ...  more