Multi-Digit Subtraction
Place Value and Regrouping
About this book
Add big numbers and know why it works.
Four modules take learners from adding hundreds, tens and ones with blocks and place-value charts to regrouping in two places and checking sums with estimates. Every module follows the same seven LessonCrest steps, with help that fades as confidence grows.
- Add by place value with blocks, charts and expanded form
- Line up digits by value before using columns
- Regroup ones, then ones and tens, with every trade explained
- Estimate, apply to stories and check a different way
- Review pages, an exit check and a short retry
- Answers that explain why, with help for common mistakes
Look inside
What this book covers
Covered
What this book covers: whole numbers with sums up to 999, using base-ten blocks, place-value charts and expanded form before the column method; estimating and checking sums.
Not covered
Not covered here: sums of 1,000 or more, decimals and money.
Before you start, you should be able to
- Read and build three-digit numbers.
- Add two numbers within 20.
- Trade 10 ones for 1 ten.
Things to have
Let learners build with blocks or sketch them (squares for hundreds, sticks for tens, dots for ones) whenever they want.
Notice
Pictures in this book are simplified learning models. Check answers with the explanations at the back of the book.
The steps in this book
- Step 1: Get Ready
Check the skills you need before you begin. If something feels tricky, an adult can help you start in the right place.
- Step 2: Learn It
Read a short, clear explanation of the new idea and the words that go with it.
- Step 3: See It
Watch the idea being used, one step at a time, in a worked example.
- Step 4: Try It Together
Practice with prompts and help cues. The help gets smaller as you get stronger.
- Step 5: On Your Own
Practice on your own with different kinds of questions, and explain your thinking.
- Step 6: Look Back
Look back at earlier learning so it stays strong, then check where to go next.
- Step 7: Check and Fix
Check your answers. Each answer explains why, names a common mistake, and shows how to fix it.
What is in the book
The modules
- Module 1: Add by place valuePages 5–14
- Module 2: Regroup onesPages 15–24
- Module 3: Regroup across placesPages 25–34
- Module 4: Estimate, apply and checkPages 35–46
Contents
- Readiness check, pp. 3–4. Before Module 1. Its table tells you where to start.
- Modules, pp. 5–46
- Checkpoints, pp. 14, 24, 34, 46. The last page of each module.
- Mixed review, pp. 47–50. Questions from across the book, mixed together.
- Exit check, pp. 51–52. A last check across the book.
- Reflect and repair, p. 53
- Try again, p. 54. Fresh questions like those in the exit check.
- Extra practice, pp. 55–56
- Answers and explanations, pp. 57–68. Notes in this part are headed “Why”, “Common mistake”, “Help” and “Look for”.