Math lesson plan · 2nd grade (Year 3 in England) · 45 minutes
Write three-digit numbers in expanded form
Number sense
CCSS 2.NBT.A.3England: Y2 Number and place valueEngland: Y3 Number and place value
Objective and success criteria
Students will: Write three-digit numbers in expanded form.
- I can answer questions on today's skill on my own, without help.
- I can explain each step and say why it works.
- I can check my answer and spot a mistake.
Before and after
Needs first: Value of each digit in a three-digit number
Leads to: Build a number from hundreds, tens and ones in any order; Rename numbers using hundreds, tens and ones
Materials: Place value chart, Base-ten blocks or a number line, Mini whiteboards and pens, Printed student sheet (below).
Warm-up · 5 min
- Quick retrieval from earlier learning (Value of each digit in a three-digit number). Students answer on mini whiteboards.
- Show answers together and note who needs support in the main task.
- In 874, what is the ones digit worth? → 4Prompt: Hundreds are on the left, then tens, then ones.
- Which number has 3 hundreds, 0 tens and 9 ones? (3009 / 309 / 39 / 390) → 309Prompt: A three-digit number has a hundreds digit, a tens digit and a ones digit.
- Which digit is in the tens place of 824? → 2Prompt: From the right: ones, tens, hundreds.
Hook · 5 min
- Show a number in the news or a price tag and ask what each digit is worth.
- Share the objective: Write three-digit numbers in expanded form. Read the success criteria together.
I do: model it · 10 min
- Work through the example out loud, saying why you do each step, not just what you do.
- Example: 489 = 400 + 80 + __
- Step 1: 489 = 400 + 80 + 9
- Step 2: 9
- Answer: 9
- Pause after each step and ask a student to say what comes next.
We do: guided practice · 10 min
- Do these together. Students try each step on whiteboards before you reveal it.
- Use the hints as prompts rather than giving the answer.
- 173 = __ + 70 + 3 → 100Prompt: Expanded form shows what each digit is worth.
- Which is 602 in expanded form? (60 + 2 / 600 + 20 / 6 + 0 + 2 / 600 + 2) → 600 + 2Prompt: 602 has 0 tens.
You do: independent practice · 10 min
- Students work on the student sheet. Circulate and check the first two answers of every student early.
- Students who finish: write a question of their own for a partner, with the answer.
The 8 questions are on the student sheet below, with answers in the key.
Exit ticket · 5 min
- Two questions on their own. Sort answers into got it / nearly / not yet to plan the next lesson.
- Sofia wrote 173 = 1 + 7 + 3. What should the first part, the hundreds, be? → 100Prompt: Does 1 + 7 + 3 really add up to 173?
- Which is 502 in expanded form? (5 + 0 + 2 / 50 + 2 / 500 + 20 / 500 + 2) → 500 + 2Prompt: 502 has 0 tens.
Watch out for
- Reading 1,045 as one thousand four hundred five: point to each place and say its value.
- Thinking a longer number is always bigger, even with decimals (0.45 vs 0.5).
Support and stretch
Support
- Review first: Value of each digit in a three-digit number.
- Use concrete materials: place value chart.
- Give the first step of each question, or a partly worked example to finish.
- Pair with a confident partner for the guided practice.
Stretch
- Move on to: Build a number from hundreds, tens and ones in any order; Rename numbers using hundreds, tens and ones.
- Explain a common mistake in writing and how to fix it.
- Write a word problem that uses today's skill, then solve a partner's.
Homework and more practice
Free online practice with hints and printable worksheets for this skill: eurekami.com/math/grade-2.
Free lesson plan from eurekami.com/lesson-plan-builder