At the earliest stages of learning, the use of a balance is sometimes not actually necessary. Young children can be shown how weight and gravity work with an experiment like the broom/chair experiment. Place two identical chairs facing each other, and put a plank across the tops of both. Then put a broom with a heavy sweeping head in a perpendicular fashion atop the plank, and hang an open-backed chair from the other end of the broom. At what point do the chair and the broom’s head balance each other out? After this, an educational balance can be used to measure the mass of several different objects.

At the next level, though, a balance is necessary to show the difference between mass and weight. Though they are both properties of matter, the two can be easily confused. Mass is the extent to which an object resists acceleration. Weight is the force by which an object is attracted by gravity. Mass resists motion, while weight causes motion. Let’s assume that two objects are falling from the sky; one of them has twice the weight of the other. They fall at the same rate, because the heavier object also has twice the resistance of the other.

A standard beam balance and a spring scale can be utilized to show how the two properties differ. Objects weighing one gram can be placed on both scales. Which is great for the classroom, but what if we were on the moon? The mass needed to balance the beam would be different than the other scale, because the spring scale measures weight ( the force of gravity), not mass.

A classroom balance can also be useful in showing American students the difference between grams and ounces. For example, students can put a paper cup full of thumbtacks on one pan of the balance and a pair of scissors on the other pan and determine how many thumbtacks it would take to match the weight of the scissors in grams. Also, students can use the balance to compare objects with similar weights but very different sizes; for example, an ingot of lead and a football. Use your imagination!