Here are two fractions: ⅔ and ¾. Hands up: which one do you think is bigger? Be ready to say how you decided. Careful, though, because just looking at the top numbers, or just the bottom numbers, can fool you.

You are about to see two fractions at a time on strips of the same length, and then four at once. We can only compare fairly when the parts are the same size, so watch what happens when each fraction is renamed to a common denominator. Then read off the order by length: the longer the shaded part, the bigger the fraction.

Three fractions are waiting on their strips below. Shade each one, then rename all three to a common denominator so the parts are the same size. Once the parts match, line the shaded strips up by length and put the whole set in order from smallest to largest. You will be asked to say how you knew, not just what the order is.

Four sets of fractions are waiting below, and each set is a step trickier than the one before. For each one, agree a common denominator, shade and rename the four fractions, then put them in order from smallest to largest. Press Check only when the class has agreed on the order.

What we learned today

• To compare fractions fairly, we rename them to a common denominator so all the parts are the same size.
• The fraction with the longer shaded strip is the bigger one — and that is not always the one with the bigger numbers.
• A bigger denominator usually means a smaller slice, because the whole is shared into more parts.

Coming up