Explain that with partial products you put the numbers of the problem one under the other. Next you can multiply them together by working from left to right. Explain that you put the largest number of the problem on top and the other number underneath. With partial products multiplication you calculate from left to right. So you start by multiplying the tens numbers. Then you multiply the ones number. You put these answers in the chart and state what the intermediate problems are. If you add up the numbers from the chart, you know what the answer is. You put this answer at the bottom of the chart. Next there is a problem in a chart, for which each time there is a different row marked in yellow. Ask the students if they know which intermediate problem belongs in each colored row. This is how you can check if students know which steps they must go through. Then you show a chart, for which the intermediate steps must be filled in. Have the students write these numbers down and hold them up so you can check their work. Then practice partial products with two more problems, one of which has the chart already filled in and the other must still be filled in.
Check whether the students can multiply partial products by asking the following questions:
- Why is it useful to be able to multiply using partial products?
- What do the letters H T O mean?
- Where do you always start when calculating partial products?
- Solve this problem using partial products: 27 × 9