Teaching this skill
Use the page after the idea is visible.
Use ten groups minus one group. For 9 × 7, think 70 − 7; then use the digit-sum pattern as a check, not as the explanation.
Before independent work, solve one example together and ask the learner to name what each number represents. During practice, prioritize accurate reasoning over speed. A short set completed with an explainable strategy gives better information than a rushed full page.

