Ray's New Primary Arithmetic · Lesson XXXVII · Unit 4: Subtraction
37. Counting back, and story problems with two steps
Goal: Your child counts backward by 2s, 3s, 4s and 5s, and solves stories that take away twice.
You'll need
- About 20 small counters: dried beans, buttons, pennies or pebbles (the book suggests marbles, beans or pebbles)
What's in the book
Exercises such as "Begin with 20, and subtract by 2's to 0", then story problems like "Mary had 11 apples: she gave 4 to Lucy, and 5 to Nancy: how many had she left?"
The lesson, step by step
Count back
Count back together from 20 by 2s to 0. Then do the other counting-back exercises on the page.
Two-step stories
Read Mary's apples problem. Act it out with counters: 11, give 4 away, give 5 away. How many left?
Another way
Show that she gave away 4 and 5, that is 9 in all, and 11 less 9 are 2. Both ways give the same answer.
Book problems
Work through the rest of the problems.
Afterwards
Unit 4 is done. Review the subtraction cards before moving on to multiplication.