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Comparing Unlike Fractions

A 50-minute Grade 4 lesson on comparing fractions with nothing in common, using benchmarks and common denominators — and knowing which to reach for.

Comparing Unlike Fractions is a free 50-minute Grade 4 maths lesson plan for Common Core standard 4.NF.A.2 — compare fractions that look different. 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 4
Length:
50 minutes
Standard:
4.NF.A.2

Grade 4 · Number & Operations — Fractions

4.NF.A.2

Compare two fractions with different numerators and different denominators, e.g., by creating common denominators or numerators.

Objective

Students will be able to compare two fractions with different numerators and denominators by creating a common denominator or reasoning with a benchmark.

Students are successful when they can

  • Compares a fraction to 1/2 as a benchmark.
  • Rewrites two fractions with a common denominator and compares them.
  • Chooses the quicker of the two methods for a given pair.

What you need

  • Fraction strips cut from a common length
  • Number lines marked 0 to 1
  • Fraction comparison cards
  • The printable practice sheet linked at the end of this plan

The lesson

Warm-up — more or less than half?

6 min
  1. Show 3/8, 5/9, 4/7, 2/5 and ask only whether each is more or less than a half.
  2. Compare the numerator with half the denominator. That is the whole benchmark method.

Teach — two tools, one choice

15 min
  1. Compare 3/8 and 5/9. One is below a half, the other above. Done, without any common denominator.
  2. Now compare 5/8 and 7/12. Both are above a half, so the benchmark gives nothing.
  3. Rewrite both over 24: 15/24 and 14/24. Now the numerators decide it.
  4. Say why 24: it is a multiple of both denominators, so both fractions can be rewritten without changing their value.
  5. Show what changing the denominator does on a number line — the point does not move, only the label.
  6. Finish with 2/3 and 3/4, comparing both ways, and ask which was quicker here.
“Try the benchmark first. It is quicker and it settles half the comparisons you will meet. When it does not, find a common denominator.”

Guided practice — pick the tool

14 min
  1. Pairs sort comparison cards into 'benchmark will do' and 'needs a common denominator' before solving any.
  2. They then solve them and check the sorting was right.
  3. Every answer is recorded with the correct symbol.

Independent practice

12 min
  1. Students complete a comparing fractions page.
  2. Comparisons made by looking at numerators or denominators alone are the diagnostic error.

Close

3 min
  1. Compare 4/9 and 5/8 and ask which method they used.
  2. The benchmark settles it in one step, and hearing that is the right ending.

What goes wrong, and why

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

Says 3/8 is greater than 2/5 because 3 and 8 are both bigger.

Why: Whole number reasoning is being applied to both parts of the fraction independently, which has no meaning for the size of the fraction.

Fix: Place both on a number line. The positions settle it, and the pupil sees that the digits were not the evidence.

Finds a common denominator but only changes the denominators.

Why: The procedure has been remembered as making the bottoms match, without the corresponding change to the top.

Fix: Show it on a number line: changing only the denominator moves the point. Both numbers must be multiplied or the fraction is a different fraction.

Always multiplies the two denominators together, even when a smaller common multiple exists.

Why: It always works, so nothing forces the extra thought. It is inefficient rather than wrong.

Fix: Compare 5/6 and 7/12 by multiplying to 72 and by using 12. Both give the right answer and one takes a fraction of the time.

If they are not there yet

  • Use fraction strips cut from the same whole for every comparison until the reasoning is secure.
  • Work with benchmark comparisons only, before introducing common denominators.

If they finish early

  • Order four fractions with unrelated denominators.
  • Find a fraction between 2/5 and 1/2.
  • Compare two fractions by finding a common numerator instead, and say when that is easier.

Exit ticket

Compare 5/12 and 4/7. Say which method you used and why.

What to look for: 4/7 is greater, ideally by the half benchmark — 5/12 is below half and 4/7 is above. A common denominator of 84 also works and is worth crediting.

Printable practice for 4.NF.A.2

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

Questions about Comparing Unlike Fractions

How long does the Comparing Unlike Fractions 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 Comparing Unlike Fractions teach?

CCSS.MATH.CONTENT.4.NF.A.2 — 4.NF.A.2, Number & Operations — Fractions for Grade 4: “Compare two fractions with different numerators and different denominators, e.g., by creating common denominators or numerators.” In plain terms, compare fractions that look different.

What do I need to teach this lesson?

Fraction strips cut from a common length, number lines marked 0 to 1, fraction comparison 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: says 3/8 is greater than 2/5 because 3 and 8 are both bigger; finds a common denominator but only changes the denominators and always multiplies the two denominators together, even when a smaller common multiple exists. 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: “Compare 5/12 and 4/7. Say which method you used and why.” 4/7 is greater, ideally by the half benchmark — 5/12 is below half and 4/7 is above. A common denominator of 84 also works and is worth crediting. 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 Comparing Unlike Fractions?

Yes — 2 printable 4.NF.A.2 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 Comparing Unlike Fractions 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 4.NF.A.2 of the Common Core State Standards for mathematics.