Ray's New Intellectual Arithmetic · Lesson V · Unit 1: Adding and subtracting in your head
5. Adding several numbers, and counting by any number
Goal: Your child adds three or more numbers in a row and counts by 2s up to 9s to about 100.
You'll need
- The book page (press “📖 Book page”, or use a printed copy)
- Paper for jotting, though the work is meant to be done in the head
What's in the book
Fifty-three problems: chains such as “Three and 6 and 4 are how many?” (modelled as “Three and six are nine, and four are thirteen”), word problems, then counting by 2s through 9s.
The lesson, step by step
Warm up
Ask three or four problems from the last lesson again, out of order. Your child answers and says why.
Show the reasoning
SayThree and six are nine, and four are thirteen.
The trick is to carry the running total and add the next number to it, saying each total aloud.
Work the problems aloud
Read each problem on the page aloud. Your child answers, then explains in a full sentence, the way the book's model solutions do. The problems go like this:
Three and 6 and 4 are how many?
A man gave 13 dollars for a cart, 9 for a plow and 1 for a rake: how much did he spend?
Begin with 3, and count to ninety-nine by adding 3 each time.
Ask “Why?”
After each answer ask “Why?” or “How do you know?” Ray's wants the reasoning said aloud, not just the number. If your child stalls, go back to the model and say the first half of the explanation together.
Wrap up
Pick the two problems that were hardest today. Tomorrow, start with those as the warm-up.
Afterwards
Do the rest of the lesson's problems over the next day or two, a few at a time. Move on when your child can explain them without help.
Answers to the book's problems
1) 13. 2) 16. 3) 13. 26) 15 cents. 27) $15. 28) 23 books. 29) $23. 30) 26. 31) 28 cents. 32) $23. 33) 33 cents. 34) 41 hogs. 35) 32 cents. 36) 34 cents. 37) 26 years. 38) 22.
Worked out for this site from the scan. If a number in your copy differs, trust the book. Every answer is in Ray's own Key ↗.