Ray's New Primary Arithmetic · Lesson XXXIII · Unit 4: Subtraction

33. Subtracting 9

Goal: Your child knows by heart every fact that takes 9 from a number up to 19, and uses them in story problems.

⏱ About 15 minutes · 7 steps

Open it at the Internet Archive ↗

You'll need

  • About 20 small counters: dried beans, buttons, pennies or pebbles (the book suggests marbles, beans or pebbles)
  • A slate, small whiteboard or paper and pencil

What's in the book

The table of facts that take 9 away, up to "9 from 19 leaves 10", then story problems. The first has a worked solution.

The lesson, step by step

  1. Warm up

    Five quick facts from the earlier subtraction tables (or, for this first one, from the addition tables).

  2. Build it with counters

    Put out 10 beans and take 9 away. How many are left? Then start with 11 and take 9 away, and so on.

    Say each fact in full: "9 from 11 leaves 2."

  3. Link to adding

    Show that 9 and 3 are 12, so 9 from 12 leaves 3. Every subtraction fact has an addition fact behind it.

  4. Read the table

    Read the table on the book page together, then alone.

  5. Cover and recall

    Cover the answers and ask the facts out of order.

  6. Story problems

    Read the problems aloud. They go like this:

    Thomas has 10 walnuts: after eating 9, how many will he have left?

    I bought a kite for 9 cents, and sold it for 18 cents: how much did I make?

    Your child answers in a full sentence.

  7. Wrap up

    Your child writes three facts from today's table from memory.

Afterwards

Two minutes a day on this table, mixed with the earlier ones.

Tip

If a fact is slow, count up from the smaller number: for 9 from 15, count from 9 up to 15.

@teddyrookbook GitHub