Like multiples, the children should be very familiar with factors and what they are. Complete the BBC Bitesize activity, watch the Corbettmaths video on factors and then work through the different activities up to Q6 on the Corbettmaths factors questions (Circles could probably leave the first worksheet).
This is optional but Circles, and possibly some Triangles, could be extended by starting to learn about common factors and identifying the highest common factor (HCF) of two or more numbers. They will find out more about these at their next school but most of the children will be more than capable of understanding them. Watch the Corbettmaths video on common factors and the HCF and have a go at Q7-13 that may have been left out on the Corbettmaths questions and the Corbettmaths common factors and HCF questions.