### Construct-o-straws

Make a cube out of straws and have a go at this practical challenge.

### Matchsticks

Reasoning about the number of matches needed to build squares that share their sides.

### Little Boxes

How many different cuboids can you make when you use four CDs or DVDs? How about using five, then six?

# Tetrahedron Faces

##### Age 7 to 11Challenge Level
Some children from Carr head Primary School sent in this solution.  It's actually a solution to a different question being asked - they worked on not having to use each of the 4 colours for each arrangement. We have included it here as it's shows a really good piece of work. Here is what they wrote:-

I am writing to you because we think that we (9 kids from Carr Head Primary School) have found a solution for your tetrahedron question and here's how we did it. Has anybody else found a solution yet?
First we split into 3 different groups,  Elliott, Ben B and Oliver were in one group but we started by making a 3D tetrahedron. Second we coloured them with all the colours properly, then we numbered the faces.
Next we put the first letters of the colours (B,G,Y,R) and put the numbers of the faces
B G Y R
1 2  3 4
Then swapped them around like 1,3,2,4 but we noticed that we were rotating it. An answer was 24 but that was wrong.
Here is the table that works. This doesn't rotate and the answer would be 10 because you only have 1 blue all the time and it needed 4 of all the colours added up.

If you try this, then do send us what you find out.