All 6 problems from "Adding Fractions" with complete step-by-step worked solutions: recognising the type, the idea, the working steps and the conclusion. Use this page to review with your child after the animated lesson, or let them check their own working against it.
Warm-up with matching pieces: 1/4 + 2/4 = ___
Key idea: Same denominators: add the tops, keep the bottom.
1/4 + 2/4 — both fractions already share the denominator 4.
The pieces are the same size, so just add the numerators.
The pieces match: quarters and quarters.
Add the tops: 1 + 2 = 3.
So: So 1/4 + 2/4 = 3/4.
What is 1/2 + 1/3?
Key idea: Different denominators: rewrite both over a common denominator first.
1/2 + 1/3 — the pieces are different sizes, so they cannot be added yet.
Rewrite both fractions over 6, then add the tops.
1/2 = 3/6 and 1/3 = 2/6.
3/6 + 2/6 = 5/6.
So: So 1/2 + 1/3 = 5/6.
2/3 + 1/6 = ___
Key idea: When one denominator divides the other, only the other fraction needs rewriting.
2/3 + 1/6 — sixths work for both, since 6 is a multiple of 3.
Rewrite 2/3 as sixths, then add.
2/3 = 4/6.
4/6 + 1/6 = 5/6.
So: So 2/3 + 1/6 = 5/6.
Subtraction works the same way: 5/6 − 1/4 = ___
Key idea: Subtraction needs the same groundwork: common denominator, then subtract the tops.
5/6 − 1/4 — different denominators again.
Rewrite both over 12, the common denominator.
5/6 = 10/12 and 1/4 = 3/12.
10/12 − 3/12 = 7/12.
So: So 5/6 − 1/4 = 7/12.
Minh eats 1/4 of a cake in the morning and 3/8 of the cake in the afternoon. In total he eats ___ of the cake.
Key idea: Different denominators: rewrite both over a common denominator first.
A story sum: 1/4 of a cake in the morning plus 3/8 in the afternoon.
Rewrite 1/4 over 8 so both parts count eighths.
1/4 = 2/8.
2/8 + 3/8 = 5/8.
So: So Minh eats 5/8 of the cake in total.
Three ribbons are joined end to end: 1/2 m, 1/3 m and 1/6 m. Their total length is ___ m.
Key idea: Three fractions: bring them ALL to one denominator.
Three ribbons joined end to end: 1/2 m, 1/3 m and 1/6 m.
Sixths work for all three denominators at once.
1/2 = 3/6, 1/3 = 2/6 and 1/6 stays 1/6.
3/6 + 2/6 + 1/6 = 6/6 = 1.
So: So the total length is 1 m.
Work out 1/2 + 1/3.
Shortcuts: Space (play), Arrow keys (step), R (reset), F (fullscreen)
Add 1/2 and 1/3. Look at the two bars: their cuts do not line up, so we cannot just count pieces to add them yet.
Unlike denominators means unlike piece sizes — counting pieces is not possible yet.
Change the numbers and watch the diagram redraw itself:
