B6 — Multiplication within 100: Automatizing Basic Facts using the Open Number Line

The first two problems in the string support children to understand the underlying structure of multiplying by tens. Remember to facilitate a discussion helping to understand what is happening to the numbers when you are multiplying to avoid a student saying, "I added a zero." There are a variety of ways the third problem might be solved. Encourage the children to share their strategies and to discuss why they work. This problem encourages students to use the underlying structure of multiplying by tens and then removing a group (in this case a group of 5). The remaining problems in this string also encourage the use of ten times. Considerable discussion might be required when children are grappling with which groups should be removed.