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Which times on a digital clock have a line of symmetry? Which look the same upside-down? You might like to try this investigation and find out!

Clock Hands

This investigation explores using different shapes as the hands of the clock. What things occur as the the hands move.

Ten Green Bottles

Do you know the rhyme about ten green bottles hanging on a wall? If the first bottle fell at ten past five and the others fell down at 5 minute intervals, what time would the last bottle fall down?

How Long Does it Take?

Age 7 to 11
Challenge Level

How Long Does it Take?

The aim of this game is to match pairs of cards. 

Click on a card in the interactivity below to turn it over. Then click on another one. If the two cards match, they will stay face-up. If the two cards do not match, they will return to being face-down. 

The game ends when all the cards have been matched in pairs. 

How do you know when a card matches another card?
Can you remember where particular cards are to help you match the pairs?


We would love to hear about the strategies you use as you play the game.

You may like to explore these alternative versions of the interactivity:

  • Play with a scoring system - you start with 100 points, lose 10 points whenever you turn over cards that don't match, and add 50 points whenever they do match.
  • Play against the clock - can you beat your personal best?
  • Play with face-up cards - the cards are all face-up at the start so you can focus on the maths rather than the memory aspect of the game.

Here is a copy of the cards for this game which you can print off to play away from the computer if you wish.

Why play this game?

This simple game is designed to help children become more familiar with standard units of time and to be able to choose the most appropriate units to measure time.  Higher-order thinking is required in order to play strategically.

Possible approach

Begin by introducing the class to the printable cards before the interactivity. Give out sets of cards to each pair of learners and encourage them to lay them all out, face-up. You could offer any of the following prompts to encourage them to engage with the representations on the cards:

  • How might you group/sort the cards?
  • How might you order the cards?
  • What is the same about the cards? What is different?
  • Take three or four cards. Which one doesn't belong? Why? Can you choose a different card which doesn't belong? Why?
  • Create another pair for the set. Can you create a pair which you think would be relatively easy to match? Can you create a pair which is harder to match? How did you decide which was easy and which was difficult.
  • Rather than giving out all the cards, you could just give out half the set of cards so that each card does not have a pair. Invite learners to create a pair for each card they have been given.
  • Share the cards out in a group of four. Take it in turns to describe what is on one of your cards without showing it to anyone else. Who has a card which shows an equivalent amount?

Once learners have explored the cards in some of these ways, show them the interactivity. You may like to begin to play the game on the interactive whiteboard with the whole group. You could choose a card and, before turning over a second card, invite learners to talk in pairs about what might match. As more cards are revealed, trying to remember which cards have already been seen and what they have on them becomes important too.

As soon as the class has a flavour of the game, suggest that they work in pairs at a computer, laptop or tablet. (They could use the printable cards if this is not feasible.) As they play in pairs, watch and listen, and make a note of anything you overhear that you'd like to refer to during a mini plenary. It may be that you notice a misconception more than once, or that you'd like to spend a few minutes inviting learners to explain how they knew that two particular cards are a match. Look out, too, for those children who begin to think strategically by using their turn wisely.  For example, where possible, it is better for the first card they turn over to be one that is unknown as there is a possibility that it will match with one that is already known.

You could return to the interactivity in subsequent lessons, perhaps as a starter or during a plenary, where appropriate.

Key questions

What might the matching pair for that card have on it?
How do you know those two cards match?
Have we already seen a card that might be a match for that one?

Possible support

Playing the game with all the cards face-up is a great way to focus on the mathematics if the memory aspect proves tricky for some children. You can do this in this version of the interactivity.

Possible extension

Some pairs may enjoy challenging themselves to get as many points as possible using this version of the interactive game and/or trying to complete the game as quickly as possible (this version of the interactivity has a timer). Some of the suggestions in the opening paragraph of the 'Possible approach' above would make good extension tasks.