Children at Underhill Junior School coped well with this problem when we went in to use the Prime site with them. Many were able to explain how they had done it very clearly. Among these were Adam & Kane, Rochelle & Matthew and William & Anthony.

Rochelle and Matthew said:

You make two "faces" with one of each colour -

Put one of the "faces" down and lay the other on top but twisted half way:

Adam, Kane, William and Anthony added that cubes the same colour must be diagonal to each other.

Pupils from Moorfield Junior School used triangular paper to draw their solutions, which worked very well. This is Emma and Abi's:

Their explanations were very similar to the ones above.