Carrying the TENS digit in a multiplication problem is a sticking point for many students. To address this, I use a task analysis approach to zero in on the step of identifying the product for the ONES as a prelude to carrying.
In the example below, 5 and 4 are in the ONES place and the product is 20. The task analysis steps involved:
- compute the product
- identify the digits in the product
- identify the digit in the ONES
- identify the digit in the TENS
- Understand that the TENS digit must be carried to the TENS column
By creating a place holder for the product and scaffolding it to differentiate between the TENS and the ONES, the student can visualize the product. This reduces the demand placed on working memory. Once mastery with the place holder is demonstrated, it can be faded (and used as necessary as part of corrective feedback).
NOTE: I started this mini-lesson for a student with ADHD by having him warm up with problems without carrying. Also, extra line below the 60 and 20 are used for multiplying by 2 digit numbers (next in the sequence).
Here is a post on how I use color coding to unpack the multiplication by 2-digit factors.
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