Take your children on a 'shape hunt' - they will need to recognise shapes in the environment. Many different abilities are catered for.
Begin by finding squares, rectangles and triangles, up to octagons and irregular quadrilaterals. You can display this on your interactive white board and have either the children just look for shapes, or trace over them with a marker.
This is a great activity to lead into your own shape hunt around your school, or possibly when children can take photos with digital cameras and save them into their own shape booklets. That's what we did and it worked great!