Which pairs of cogs let the coloured tooth touch every tooth on the other cog? Which pairs do not let this happen? Why?
Choose a couple of the sequences. Try to picture how to make the next, and the next, and the next... Can you describe your reasoning?
You are organising a school trip and you need to write a letter to parents to let them know about the day. Use the cards to gather all the information you need.
Complete these two jigsaws then put one on top of the other. What happens when you add the 'touching' numbers? What happens when you change the position of the jigsaws?
Use a single sheet of A4 paper and make a cylinder having the greatest possible volume. The cylinder must be closed off by a circle at each end.
These clocks have only one hand, but can you work out what time they are showing from the information?
What happens to the area and volume of 2D and 3D shapes when you enlarge them?
In this challenge, you will work in a group to investigate circular fences enclosing trees that are planted in square or triangular arrangements.
Group work depends on effective team work. This article describes attributes of effective team work and links to "Team Building" problems that can be used to develop learners' team working skills.
Although almost any NRICH activity could be tackled in a group, these upper primary activities have been created specifically with group work in mind.
This article for teachers suggests a range of activities to help children get better at working in groups.
In this article for teachers, Jennie Pennant outlines how group-worthy tasks support the development of children's problem-solving skills.