We will be finishing up Chapter 8 this week.  In this chapter, your student is learning to add and subtract tens. Students will begin by finding 10 more or 10 less than a number. They will then add and subtract tens using various strategies including number lines, quick sketches, and using addition to subtract. The vocabulary phrase associated with this chapter is open number line.

We played some math games on Friday.  Ask your student to show you how to play poison and top it.  These are great games to help build mental math awareness.

To practice adding and subtracting tens with your student, use everyday items found in packages that contain multiple items, such as straws, paper clips, or toothpicks.

When you notice such a package, either at home or while shopping, ask questions like these.

• To practice using mental math to find 10 more or 10 less, have your student find the number of items in the package. Then ask, “How many crayons are in that box? What is 10 more than that number? What is 10 less than that number?”
• Show your student the number of items, then say that you need a certain multiple of 10 more (20, 30, 40, etc.), not exceeding a total of 100. For example, point out that there are 12 eggs in a carton. Ask, “How many eggs would there be if I bought 50 more?” Encourage your student to explain the strategy used to find the total. Repeat, using subtraction. Say, “There are 75 beads in this package. If we use 30 for a project, how many will be left? What if we use 60?”
• To reinforce the connection between addition and subtraction, ask your student what addition equation can be used to solve a subtraction problem. Ask, “There are 60 party cups in this package. We need 20 for tomorrow’s picnic. What addition equation can you use to find how many cups will be left?”
• Model other scenarios and have your student discuss how to use an open number line, quick sketch, or mental math to find the sum or difference.

By the end of this chapter, your student should feel confident with the learning targets and success criteria on the next page. Encourage your student to think of other opportunities to practice adding and subtracting tens.

Have a great time adding and subtracting tens!