Ray's New Primary Arithmetic · Lesson LXVIII · Unit 7: Signs, bigger numbers and mixed problems
68. Story problems with bigger numbers: taking away
Goal: Your child solves subtraction stories with numbers up to about 50, including "how many more?"
You'll need
- A slate, small whiteboard or paper and pencil
What's in the book
Fourteen problems such as "Thomas had 15 marbles, and lost 4: how many has he left?" and "Henry had 10 cents, and his mother gave him enough to make 40: how much did she give?"
The lesson, step by step
Count up
For Henry: from 10 to 40 is 3 tens, so 30 cents. Counting up is a good way to subtract.
Work through the page
Your child answers each in a full sentence.
Afterwards
Ask "How many more until ...?" questions about real things: pages left in a book, days until a birthday.