The transition from 9 to 10 is pivotal in understanding counting to 100 and later on for regrouping in addition and subtraction.

On the worksheets, the students will practice writing the numbers on the lines. I left in a few numbers to make sure your student doesn't miss any.

The writing exercises show open fours, while closed fours are used in most problems on the worksheets. Open fours are usually easier for students to write. Your student should recognize fours and ones in both the handwritten and printed forms and know that both forms mean the same thing.

You can also use the first two houses in Decimal Street (lesson 1) to teach counting to 20. Begin by placing one green unit block in the units house and saying and writing 1. Add another unit block and say and write 2. Keep doing this until there are 9 at home in the units house. Then try to add one more unit and notice that there is no more room. The reality at this point is that the 10 individual green units must be transformed into a blue ten bar to make room.

To make it more interesting, we can make up a story about these new units who keep moving into our neighborhood. Apparently they heard that we have a nice home, and naturally they want to live with us. After we welcome them into our home, we find that we like them as well. However, when the house is full (nine units) and a new fellow wants to live with us, we have a family discussion. We decide that in order for him to live with us, we will all have to become a blue ten bar and move into the house next door. That way we can all be together.

As more units arrive, they can stay in the units house because it is now open. When the first unit arrives after we have moved into the tens house, we have one ten bar and one unit bar, or 11 . The next one arrives and there are 12-one ten and two units-living on our street. Eventually we have 19 units. When the next one arrives, another 10 is formed and moves in with the original 10 , so now there are two tens, or 20. This is illustrated on the next page.

When counting to 20 , encourage the student to count aloud using the common names: "one, two . . . eight, nine, ten, eleven, twelve . . . twenty," as well as with the place value names: "eight, nine, onety, onety-one, onety-two . . . two-ty." The common names are used most often, but the place value names can help the student understand the concept.