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Rounding Decimals

A 50-minute Grade 5 lesson on rounding decimals to any place, using the same two-neighbours method that works for whole numbers, because it is the same idea.

Rounding Decimals is a free 50-minute Grade 5 maths lesson plan for Common Core standard 5.NBT.A.4 — round decimals. It is timed across 5 sections, gives the exact wording to use where the wording carries the mathematics, names 3 misconceptions with the teaching move that addresses each, and ends with an exit ticket and a printable worksheet with its answer key.

Grade:
Grade 5
Length:
50 minutes
Standard:
5.NBT.A.4

Grade 5 · Number & Operations in Base Ten

5.NBT.A.4

Use place value understanding to round decimals to any place.

Objective

Students will be able to round a decimal to any given place using place value understanding.

Students are successful when they can

  • Names the two decimals a number sits between for a given place.
  • Rounds to the nearest whole, tenth and hundredth.
  • Explains why 3.7 rounds to 4 rather than to 3.

What you need

  • Number lines marked in tenths and hundredths
  • Place value charts extended to thousandths
  • Decimal number cards
  • The printable practice sheet linked at the end of this plan

The lesson

Warm-up — between which two?

6 min
  1. Give 3.68 and ask which two whole numbers it sits between, then which two tenths.
  2. 3 and 4; 3.6 and 3.7. Naming the neighbours is the entire method.

Teach — same method, smaller landmarks

15 min
  1. Draw a number line from 3 to 4 and mark 3.68. Nearer 4, so it rounds to 4.
  2. Zoom in: a line from 3.6 to 3.7 with 3.68 marked. Nearer 3.7.
  3. Zoom again: 3.68 is already a hundredth, so rounding to hundredths leaves it alone.
  4. Now 3.649 to the nearest tenth. Neighbours 3.6 and 3.7, and it is nearer 3.6 — the 4 decides, not the 9 after it.
  5. Say that clearly: only the digit immediately after the target place decides, because the rest cannot bridge the gap.
  6. Finish with 2.97 to the nearest tenth. It rounds to 3.0, and the whole number changed.
“Draw the two neighbours. It is the same method you used for whole numbers, because rounding is always about which landmark you are nearer.”

Guided practice — neighbours before answers

14 min
  1. Pairs round each decimal to two different places, writing the neighbours first.
  2. The partner checks the neighbours are genuine multiples of the target place.
  3. Include several where rounding up carries into the next place.

Independent practice

12 min
  1. Students complete a rounding decimals page.
  2. Rounding 3.649 to 3.7 by rounding the 9 first, then the 4, is the diagnostic error.

Close

3 min
  1. Round 4.96 to the nearest tenth.
  2. 5.0, and the fact that the whole number changed is the note to end on.

What goes wrong, and why

Each of these is a reasoning error rather than carelessness. The fix addresses the reasoning.

Rounds 3.649 to the nearest tenth as 3.7 by rounding the 9 up first.

Why: Rounding has been applied repeatedly from the right, which cascades. Each step looks correct in isolation.

Fix: Write the two neighbours. 3.649 sits between 3.6 and 3.7 and is clearly nearer 3.6, whatever the last digit is doing.

Says 3.7 rounds to 3 because 'you drop what comes after the point'.

Why: Truncation has been mistaken for rounding, and it does produce a whole number.

Fix: Put 3.7 on a line between 3 and 4. It is closer to 4, and rounding means choosing the nearer landmark.

Writes 4.96 rounded to the nearest tenth as 5, dropping the tenths place.

Why: The answer is a whole number, so the trailing zero looks unnecessary.

Fix: Ask what place was being rounded to. Tenths, so the answer is written to tenths: 5.0. The zero records the precision.

If they are not there yet

  • Round to the nearest whole number first, with the number line drawn and both neighbours labelled.
  • Use a place value chart and underline the target digit before starting.

If they finish early

  • Find the largest and smallest decimals that round to 4.3 to the nearest tenth.
  • Round to thousandths.
  • Estimate a decimal sum by rounding both numbers, and say whether the estimate is high or low.

Exit ticket

Round 7.348 to the nearest tenth and to the nearest whole number. Write the neighbours for each.

What to look for: 7.3 with neighbours 7.3 and 7.4; 7 with neighbours 7 and 8. An answer of 7.4 means the digits were rounded from the right in sequence.

Printable practice for 5.NBT.A.4

Free to print and copy, answer key included. Each sheet can generate a fresh set of problems for a retake.

Questions about Rounding Decimals

How long does the Rounding Decimals lesson take?

50 minutes, split across 5 timed sections: warm-up 6 min, teach 15 min, guided practice 14 min, independent practice 12 min, close 3 min. The minutes are stated per section and add up to the stated length, so the plan can be cut or extended at a section boundary rather than abandoned halfway.

Which standard does Rounding Decimals teach?

CCSS.MATH.CONTENT.5.NBT.A.4 — 5.NBT.A.4, Number & Operations in Base Ten for Grade 5: “Use place value understanding to round decimals to any place.” In plain terms, round decimals.

What do I need to teach this lesson?

Number lines marked in tenths and hundredths, place value charts extended to thousandths, decimal number cards and the printable practice sheet linked at the end of this plan. Everything listed is either ordinary classroom equipment or a free printable from this site — there is nothing to buy and nothing to prepare beyond photocopying.

What mistakes should I expect in this lesson?

Three, each a reasoning error rather than carelessness: rounds 3.649 to the nearest tenth as 3.7 by rounding the 9 up first; says 3.7 rounds to 3 because 'you drop what comes after the point' and writes 4.96 rounded to the nearest tenth as 5, dropping the tenths place. The plan gives the thinking behind each one and the teaching move that addresses the thinking rather than the symptom.

How do I know whether the lesson worked?

The exit ticket asks: “Round 7.348 to the nearest tenth and to the nearest whole number. Write the neighbours for each.” 7.3 with neighbours 7.3 and 7.4; 7 with neighbours 7 and 8. An answer of 7.4 means the digits were rounded from the right in sequence. That tells you whether the class needs a reteach or a thirty-second conversation before you plan tomorrow.

Is there a worksheet to go with Rounding Decimals?

Yes — 2 printable 5.NBT.A.4 worksheets, linked at the end of the plan and free like the rest of the site. Each one comes with an answer key and 25 versions, so the practice after the lesson can be a different paper on every desk.

Is Rounding Decimals free to use?

Yes. The plan, its printables and their answer keys are free to read, print and photocopy for your own class, with no account and no email capture. It was last reviewed on 5 September 2026. Please do not resell it or republish it as your own.

Last reviewed 2026-09-05. Aligned to 5.NBT.A.4 of the Common Core State Standards for mathematics.