About this book
Subtract big numbers and know why it works.
Four modules take learners from taking away hundreds, tens and ones with blocks and place-value charts to regrouping across zeros and checking every difference with addition. Every module follows the same seven LessonCrest steps, with help that fades as confidence grows.
- Subtract by place value with blocks, charts and expanded form
- Take-away and compare stories with bar models
- Regroup a ten or a hundred, with every trade explained
- Regroup across zero, one exchange at a time
- Estimate, then check differences with addition
- Review pages, an exit check and answers that explain why
Look inside
What this book covers
Covered
What this book covers: whole numbers up to 999, using base-ten blocks, place-value charts, expanded form and bar models before the column method; take-away and compare problems; estimating and checking.
Not covered
Not covered here: numbers of 1,000 or more, negative numbers, decimals and money.
Before you start, you should be able to
- Read and build three-digit numbers.
- Subtract within 20.
- Trade 1 ten for 10 ones, 1 hundred for 10 tens.
Things to have
Let learners build the first number with blocks and really trade a rod or a flat 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: Subtract by place valuePages 5–14
- Module 2: Regroup one placePages 15–24
- Module 3: Regroup across zeroPages 25–34
- Module 4: Choose, apply and verifyPages 35–45
Contents
- Readiness check, pp. 3–4. Before Module 1. Its table tells you where to start.
- Modules, pp. 5–45
- Checkpoints, pp. 14, 24, 34, 45. The last page of each module.
- Mixed review, pp. 46–49. Questions from across the book, mixed together.
- Exit check, pp. 50–51. A last check across the book.
- Reflect and repair, p. 52
- Try again, p. 53. Fresh questions like those in the exit check.
- Extra practice, p. 54
- Answers and explanations, pp. 55–66. Notes in this part are headed “Why”, “Common mistake”, “Help” and “Look for”.