摘要
INVESTIGATE The scale at the right is balanced,and the bag contains a certain number of blocks.1.Suppose you cannot look in the bag.How can you find the number of blocks in the bag?2.In what way is a balanced scale like an equation?3.What does it mean to solve an equation?To solve an cquation using models,you can use these steps.·You can add or subtract the same number of counters from each side of the mat.·You can add or subtract zero from each side of the mat.ACTIVITY Work with a partner.
