Math lesson plan · 4th grade (Year 5 in England) · 45 minutes
Rounding: greatest and least possible numbers
Number sense
CCSS 4.NBT.A.3England: Y5 Number and place value
Objective and success criteria
Students will: Rounding: greatest and least possible numbers.
- 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: Round multi-digit numbers; Rounding puzzles: which numbers round to …?
Leads to: Round whole numbers to any degree of accuracy
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 (Round multi-digit numbers; Rounding puzzles: which numbers round to …?). Students answer on mini whiteboards.
- Show answers together and note who needs support in the main task.
- Round 3795 to the nearest 100. → 3800Prompt: Which two multiples of 100 is it between?
- What is the smallest whole number that rounds to 450 when rounded to the nearest 10? → 445Prompt: Halfway between two multiples of 10 rounds up.
- A stadium recorded 542 379 visitors this season. Round this to the nearest hundred thousand. → 500000Prompt: The hundred-thousands digit is the first digit.
Hook · 5 min
- Show a number in the news or a price tag and ask what each digit is worth.
- Share the objective: Rounding: greatest and least possible numbers. 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: A number rounds to 150 000 to the nearest 10 000. What is the greatest whole number it could be?
- Step 1: 155 000 would round up, so go one less.
- Step 2: 154 999
- Answer: 154999
- 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.
- A number rounds to 5000 to the nearest 1000. What is the greatest whole number it could be? → 5499Prompt: Find the halfway points 4500 and 5500.
- Round 627 478 to the nearest hundred thousand. → 600000Prompt: Underline the digit in the place you are rounding to.
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.
- Round 959 295 to the nearest hundred thousand. → 1000000Prompt: Underline the digit in the place you are rounding to.
- A number rounds to 150 000 to the nearest 10 000. What is the greatest whole number it could be? → 154999Prompt: Find the halfway points 145 000 and 155 000.
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: Round multi-digit numbers.
- 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: Round whole numbers to any degree of accuracy.
- 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-4.
Free lesson plan from eurekami.com/lesson-plan-builder