Equivalent fractions and comparison

Key idea: Equivalent fractions name the same amount of the same whole. Split or combine equal parts to compare them.

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Cut each half in two

Cut every piece in two. Does the amount change?

The marked amount stays the same

Each full strip is one equal-sized whole.

Equal wholes. Split each half into two equal parts.
Figure data

This table is included in print while it is open.

Equal parts in the picture
WholeParts in order
Halvesmarked; empty
Quartersmarked; marked; empty; empty

One half becomes two quarters. The marked lengths match: 1/2 = 2/4.

The numerator is the top number. The denominator is the bottom number. Cut every old part into equal pieces. Multiply both counts by the same whole number above zero. Split each third in two: 2/3 = 4/6. Split each third in four instead: 2/3 = 8/12.

Changing only the numerator changes the amount. Two thirds is not four thirds.

Rename two thirds

Practise

Check your understanding 1

Change the pieces, keep the amount

Rename this amount

Each full strip is one equal-sized whole.

Keep the whole and the marked amount. Use a different denominator.
Figure data

This table is included in print while it is open.

Equal parts in the picture
WholeParts in order
Thirdsmarked; marked; empty

Write a fraction equal to 2/3 with a different denominator. Use a slash, as in 1/5. More than one answer works.

Explain how both counts change, aloud or on paper.

How can you rename two thirds without changing its value?

Show some answersHide answer

One way to cut new pieces

Each full strip is one equal-sized whole.

Each third becomes two sixths. The marked lengths still match.
Figure data

This table is included in print while it is open.

Equal parts in the picture
WholeParts in order
Thirdsmarked; marked; empty
Sixthsmarked; marked; marked; marked; empty; empty

4/6 works: multiply both counts by two. 6/9 works too: multiply both by three. Copying 2/3 keeps the value. But you have not changed the pieces.

Group pieces to simplify

Group smaller parts into larger parts

Each full strip is one equal-sized whole.

Four twelfths make one third. The whole and the marked amount stay fixed.
Figure data

This table is included in print while it is open.

Equal parts in the picture
WholeParts in order
Twelfthsmarked; marked; marked; marked; marked; marked; marked; marked; empty; empty; empty; empty
Thirdsmarked; marked; empty

The 12 small parts make 3 groups of four. The 8 marked parts make 2 of those groups. So 8/12 = 2/3.

In simplest form, no whole number above one divides both counts exactly. To simplify, divide both counts by the same factor.

Check the fraction names

Check your understanding 2

Same amount, different name

One record is wrong. Choose its row and write the correct answer.

Compare each written answer with its given task.
RowGiven taskWritten answer
A
A fraction equal to 3/5, using a different denominator
3/5
B
A fraction equal to 2/7, using a different denominator
6/21
Show one correctionHide answer

A needs a different name. For example, 3/5 = 6/10. Split every fifth into two tenths; both counts double.

Different pieces, the same marked length

Each full strip is one equal-sized whole.

Equal-sized wholes. Each fifth becomes two tenths.
Figure data

This table is included in print while it is open.

Equal parts in the picture
WholeParts in order
Fifthsmarked; marked; marked; empty; empty
Tenthsmarked; marked; marked; marked; marked; marked; empty; empty; empty; empty

Other answers, such as 9/15, work too. Copying 3/5 does not change the denominator. B already works: 2/7 = 6/21.

Use the top or bottom number shown

For 3/5 = Box/10, five doubles to ten. Double three too: the missing numerator is 6.

For 2/3 = 6/(Box), two triples to six. Triple three too: the missing denominator is 9.

Check your understanding 3

Which number is already there?

Write each complete fraction. Keep its value. Use the top or bottom number shown.

Three quarters must have numerator 9. What must you do?

Show answerHide answer

3/4 = 9/12: multiply both counts by three.

1/2 = 4/8: multiply both counts by four.

3/4 has the right value for the first task. But its top number does not match the question. Check both the value and the number shown.

Compare equal-sized pieces

How can you compare different-sized pieces?

Compare the marked amounts

Each full strip is one equal-sized whole.

The wholes have equal lengths. The pieces have different sizes.
Figure data

This table is included in print while it is open.

Equal parts in the picture
WholeParts in order
Thirdsmarked; marked; empty
Quartersmarked; marked; marked; empty

What sign belongs between 2/3 and 3/4? Write <, > or =. You can also write less than, greater than or equal to.

Show the common unitHide answer

Now the pieces match

Each full strip is one equal-sized whole.

Both wholes are split into twelfths. Compare the marked parts.
Figure data

This table is included in print while it is open.

Equal parts in the picture
WholeParts in order
First amountmarked; marked; marked; marked; marked; marked; marked; marked; empty; empty; empty; empty
Second amountmarked; marked; marked; marked; marked; marked; marked; marked; marked; empty; empty; empty

2/3 = 8/12 and 3/4 = 9/12. So 2/3 < 3/4. Count the same-sized pieces.

Match different fraction names

Compare these marked lengths

Each full strip is one equal-sized whole.

Equal wholes, cut into different pieces.
Figure data

This table is included in print while it is open.

Equal parts in the picture
WholeParts in order
Quartersmarked; marked; empty; empty
Sixthsmarked; marked; marked; empty; empty; empty

Check the amount, then the sign

Check your understanding 4

Fix one comparison

Compare both cards

Each full strip is one equal-sized whole.

Same-sized wholes.
Figure data

This table is included in print while it is open.

Equal parts in the picture
WholeParts in order
A · 3/8marked; marked; marked; empty; empty; empty; empty; empty
A · 2/3marked; marked; empty
B · 2/5marked; marked; empty; empty; empty
B · 5/6marked; marked; marked; marked; marked; empty

A · 3/8 > 2/3

B · 2/5 < 5/6

See the amounts in equal partsHide answer

A needs less than. Rename both amounts using twenty-fourths.

Now both amounts use twenty-fourths

Each full strip is one equal-sized whole.

Keep the same whole and marked lengths. Compare the counts of equal parts.
Figure data

This table is included in print while it is open.

Equal parts in the picture
WholeParts in order
First amountmarked; marked; marked; marked; marked; marked; marked; marked; marked; empty; empty; empty; empty; empty; empty; empty; empty; empty; empty; empty; empty; empty; empty; empty
Second amountmarked; marked; marked; marked; marked; marked; marked; marked; marked; marked; marked; marked; marked; marked; marked; marked; empty; empty; empty; empty; empty; empty; empty; empty

3/8 = 9/24 and 2/3 = 16/24. Nine twenty-fourths is less than sixteen twenty-fourths.

B already works: two fifths is less than five sixths. The pieces differ in size. A bigger top number alone cannot tell you which is greater.

Compare the empty parts

Read the part named in the question. Here, compare the blank space.

Check your understanding 5

Compare the blank parts

Look at the unmarked parts

Each full strip is one equal-sized whole.

The wholes are the same size. Shaded parts are marked.
Figure data

This table is included in print while it is open.

Equal parts in the picture
WholeParts in order
Amarked; empty; empty; empty
Bmarked; marked; empty; empty; empty; empty
See the blank amounts in equal partsHide answer

The blank amounts are 3/4 of A and 4/6 of B.

Now stripe only the original blank amounts

Each full strip is one equal-sized whole.

Keep the same whole. The blank lengths are shown shaded here, using twelfths.
Figure data

This table is included in print while it is open.

Equal parts in the picture
WholeParts in order
Blank amount of Amarked; marked; marked; marked; marked; marked; marked; marked; marked; empty; empty; empty
Blank amount of Bmarked; marked; marked; marked; marked; marked; marked; marked; empty; empty; empty; empty

3/4 = 9/12 > 8/12 = 4/6. Three bigger blank pieces can cover more than four smaller ones.

What is left after removal?

Crossed-out parts have gone. Compare only the marks that remain.

Check your understanding 6

Compare what is left

Compare the marks left in A and B

Each full strip is one equal-sized whole.

Same-sized wholes. Crossed-out parts are removed.
Figure data

This table is included in print while it is open.

Equal parts in the picture
WholeParts in order
Amarked; marked; removed; removed; removed; empty
Bmarked; marked; removed; empty
See the amounts left in equal partsHide answer

There are two marks left in each whole. Their pieces have different sizes.

Keep only the marks that remain

Each full strip is one equal-sized whole.

Same-sized wholes, now using twelfths. Crossed-out parts are left out of the marked amount.
Figure data

This table is included in print while it is open.

Equal parts in the picture
WholeParts in order
Marks left in Amarked; marked; marked; marked; empty; empty; empty; empty; empty; empty; empty; empty
Marks left in Bmarked; marked; marked; marked; marked; marked; empty; empty; empty; empty; empty; empty

2/6 = 4/12 < 6/12 = 2/4. The whole of A still has six equal parts. Removing marks does not change its denominator.

Can top numbers settle it?

Sam says, “A larger top number always means a larger fraction.” Look at these same-sized wholes.

Fewer pieces can cover more

Each full strip is one equal-sized whole.

Two larger thirds cover more than three smaller fifths. The whole stays the same size.
Figure data

This table is included in print while it is open.

Equal parts in the picture
WholeParts in order
Two thirdsmarked; marked; empty
Three fifthsmarked; marked; marked; empty; empty

2/3 > 3/5, although 2 < 3. The top number counts pieces. The bottom number tells us their size. We need both to compare the amounts.

Find a pair that breaks the rule

Choose a fraction with a smaller top number but greater value.

Check your understanding 7

Make a pair that breaks the shortcut

Make the first fraction greater than the second, even though its top number is smaller.

Use fractions in simplest form between 0 and 1. Use bottom numbers from 2 to 6. Keep the same whole.

Write each fraction with a slash.

Show another counterexampleHide answer

Compare the amounts in tenths

Each full strip is one equal-sized whole.

Same-sized wholes. One half covers five tenths; two fifths covers four tenths.
Figure data

This table is included in print while it is open.

Equal parts in the picture
WholeParts in order
One halfmarked; marked; marked; marked; marked; empty; empty; empty; empty; empty
Two fifthsmarked; marked; marked; marked; empty; empty; empty; empty; empty; empty

1/2 > 2/5, although 1 < 2. Five tenths is greater than four tenths. Here the larger top number names a smaller amount. Its pieces are smaller.

Other pairs work too. One pair can show why an “always” rule fails. This does not make the opposite rule true. A larger top number does not always mean a smaller fraction.

Choose an amount between two others

Where does your fraction fit?

Leave room on both sides

Each full strip is one equal-sized whole.

Equal-sized wholes. Find an amount longer than the first marked part. It must be shorter than the second.
Figure data

This table is included in print while it is open.

Equal parts in the picture
WholeParts in order
One quartermarked; empty; empty; empty
One halfmarked; empty

Between means greater than the first amount and less than the second. The two ends do not count.

See one way using eighthsHide answer

The middle amount fits both comparisons

Each full strip is one equal-sized whole.

One quarter is two eighths. One half is four eighths. Three eighths fits between them.
Figure data

This table is included in print while it is open.

Equal parts in the picture
WholeParts in order
One quartermarked; marked; empty; empty; empty; empty; empty; empty
One possible amountmarked; marked; marked; empty; empty; empty; empty; empty
One halfmarked; marked; marked; marked; empty; empty; empty; empty

1/4 = 2/8 < 3/8 < 4/8 = 1/2. The marked part has room on both sides. Four eighths would reach the upper end.

Find a fraction between two fifths and three quarters

Check your understanding 8

Make both comparisons true

Choose your own marked amount

Each full strip is one equal-sized whole.

Equal-sized wholes. Your fraction must be greater than two fifths. It must be less than three quarters.
Figure data

This table is included in print while it is open.

Equal parts in the picture
WholeParts in order
Two fifthsmarked; marked; empty; empty; empty
Three quartersmarked; marked; marked; empty

Write a fraction that fits: 2/5 < square < 3/4. More than one answer works.

Show some possible fractionsHide answer

1/2, 3/5 and 2/3 all work. Each is greater than 2/5 and less than 3/4. Equivalent names, such as 5/10 for 1/2, work too.

Neither end works as your answer. Both signs are less than. Neither sign allows equal amounts.

Check your understanding 9

Order unlike fractions

Put 1/2, 5/6 and 2/3 in both orders. Separate fractions with commas. Or use < signs for smallest first. Use > signs for largest first.

Which common unit can compare halves, thirds and sixths?

Show answerHide answer

Use sixths: 1/2 = 3/6 and 2/3 = 4/6. Five sixths already uses that unit.

Increasing: 1/2 < 2/3 < 5/6.

Decreasing: 5/6 > 2/3 > 1/2.

Each order uses all three values. Equivalent fraction names work too.

Make room for one more fraction

A, B and C already increase. Where does D belong? Compare D with the cards on either side of its new place.

Check your understanding 10

Place the new card

One card to place

Each full strip is one equal-sized whole.

Same-sized wholes. A, B and C: smallest first.
Figure data

This table is included in print while it is open.

Equal parts in the picture
WholeParts in order
A · 1/4marked; empty; empty; empty
B · 1/2marked; empty
C · 5/6marked; marked; marked; marked; marked; empty
D · 2/3marked; marked; empty
Show D's placeHide answer

The complete order in twelfths

Each full strip is one equal-sized whole.

Same-sized wholes and same-sized pieces. The marked lengths increase.
Figure data

This table is included in print while it is open.

Equal parts in the picture
WholeParts in order
A · one quartermarked; marked; marked; empty; empty; empty; empty; empty; empty; empty; empty; empty
B · one halfmarked; marked; marked; marked; marked; marked; empty; empty; empty; empty; empty; empty
D · two thirdsmarked; marked; marked; marked; marked; marked; marked; marked; empty; empty; empty; empty
C · five sixthsmarked; marked; marked; marked; marked; marked; marked; marked; marked; marked; empty; empty

Three, six, eight, ten twelfths: A, B, D, C. D goes third. The other cards keep their order.

Build your own order

Choose the fractions yourself. Compare each pair of neighbours. Check that your fractions meet every rule.

Check your understanding 11

Three fractions, your choice

Make three different fractions between 0 and 1 in simplest form, smallest first. Use bottom numbers from 2 to 6, with at least two different top numbers and two different bottom numbers. Write each fraction using a slash.

Show one possible orderHide answer

One choice, compared in equal parts

Each full strip is one equal-sized whole.

Three, six and eight twelfths increase. These are equal-sized wholes.
Figure data

This table is included in print while it is open.

Equal parts in the picture
WholeParts in order
One quartermarked; marked; marked; empty; empty; empty; empty; empty; empty; empty; empty; empty
One halfmarked; marked; marked; marked; marked; marked; empty; empty; empty; empty; empty; empty
Two thirdsmarked; marked; marked; marked; marked; marked; marked; marked; empty; empty; empty; empty

1/4 < 1/2 < 2/3 works. All three are in simplest form, between zero and one. Their bottom numbers are in range. Both top and bottom numbers vary.

The twelfths in the picture help us compare. Write the simplest forms in the boxes. Twelfths are outside this task’s chosen bottom-number range.

A different answer, 1/3 < 3/5 < 5/6, also works. One third is below one half. Three fifths is 18/30. That is less than five sixths, 25/30.

Find and repair a wrong order

Smallest first. Check each row from left to right.

Which row stops increasing?

A: 3/4; 1/2; 2/3. B: 1/3; 3/5; 5/6.

Smallest first. Same-sized wholes. Fix one row.
Figure data

This table is included in print while it is open.

Values shown on the cards
SetValues
A3/4; 1/2; 2/3
B1/3; 3/5; 5/6
Show answerHide answer

A needs fixing. Three quarters is greater than one half. It cannot go first.

Use the same-sized pieces to rebuild the order

Each full strip is one equal-sized whole.

Equal-sized wholes. Six, eight and nine twelfths show the repaired order.
Figure data

This table is included in print while it is open.

Equal parts in the picture
WholeParts in order
One halfmarked; marked; marked; marked; marked; marked; empty; empty; empty; empty; empty; empty
Two thirdsmarked; marked; marked; marked; marked; marked; marked; marked; empty; empty; empty; empty
Three quartersmarked; marked; marked; marked; marked; marked; marked; marked; marked; empty; empty; empty

1/2 = 6/12 < 8/12 = 2/3 < 9/12 = 3/4.

Row B already increases: 1/3 < 3/5 < 5/6.

Repair a new order

Check your understanding 12

Repair one row

Check both rows

A: 1/6; 3/8; 2/3. B: 5/6; 1/4; 2/5.

Smallest first. Same-sized wholes. Fix one row.
Figure data

This table is included in print while it is open.

Values shown on the cards
SetValues
A1/6; 3/8; 2/3
B5/6; 1/4; 2/5

Use commas between fractions.

Show the repaired rowHide answer

B: 1/4 < 2/5 < 5/6.

One quarter is 5/20 and two fifths is 8/20. Then 2/5 < 1/2 < 5/6, so five sixths goes last. Equivalent names, such as 2/8,4/10,10/12, work too.

A already works: 1/6 = 4/24 < 9/24 = 3/8 < 16/24 = 2/3.

Does the shortcut always work?

Test Mia’s shortcut

Mia says 6/10 = 3/5. She subtracted three from the top and five from the bottom. Does her method always make equivalent fractions?

Show answerHide answer

The equality is true. To explain it, divide both counts by two. Subtracting different amounts does not always work. It would change 4/5 to 1/0. That is not a valid fraction.

Rename nine twelfths in simplest form

Check your understanding 13

Hold the marked amount fixed

Rename the marked amount

Each full strip is one equal-sized whole.

Twelve equal parts of one whole. Keep the marked length fixed.
Figure data

This table is included in print while it is open.

Equal parts in the picture
WholeParts in order
Twelfthsmarked; marked; marked; marked; marked; marked; marked; marked; marked; empty; empty; empty

Name the marked fraction in simplest form. Split this same whole into four equal parts. How many would be marked?

Why does 9/12 become 3/4?

Show answerHide answer

9/12 = 3/4: divide both counts by three. You would mark three of the four larger quarters. The pieces changed. The marked amount stayed the same.

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Pip’s synthetic voice uses the University of Edinburgh’s Alba speech dataset, via Piper’s Alba voice, under CC BY 4.0. Audio is optional.

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