Jars and Jars - Interpret relationships to compare weights

In each problem, two pan balances are shown with jars of different types. All jars of the same type have the same weight. Students have to figure out the relative weights of objects from the relationships displayed in the pan balances. To begin, be sure that students recognize differences in the types of jars. Draw students’ attention to the position of the pans. If the two pans are not at the same level, then one pan–the lower one is heavier. If the pans are level, then they hold equal weight. One of the difficulties students often experience is recognizing that if one block (call it ) has the same weight as, for example, two others, , then the one block is heavier. Point out to students that stands for pounds, and that all jars with the same letter are the same number of pounds.

Solutions

is more than 5 pounds.

is more than 6 pounds.

is more than 3 pounds

is less than 4 pounds

is more than 3 pounds

is less than 8 pounds

What could be the weight? Tell how you figured it out.