The children should be very familiar with multiples and what they are. Complete the BBC Bitesize activity, watch the Corbettmaths video on multiples and then work through the different activities (Circles could probably leave the first two; Triangles the first one). It may be worth looking at the rules of divisibility poster to help identifying larger multiples that go beyond the usual times table facts.
This is optional but Circles, and possibly some Triangles, could be extended by starting to learn about common multiples and identifying the lowest common multiple (LCM) of two or more numbers. They will find out more about these at their next school but most of the children would be more than capable of understanding them. Watch the Corbettmaths video on common multiples and the LCM and have a go at the two worksheets.