The Maths-is-Fun site includes tessellation activities which are suitable for KS2 pupils.
It looks at regular tessellations and uses a very simple tool to create simple tessellations based on triangles, rectangles and hexagons. Extended activities include semi-regular and complex tessellations which can be enhanced with colour from a painting programme.
This site could be used for summer holiday homework as there is plenty to study and questions to respond to.
Tessellation Studies for Key Stage 2
The tessellations are created by a far more complex tool called The Tessellation Artist