Light table play with translucent magnetic tiles

What backlighting changes

Held up to the light, a translucent panel stops being a wall and becomes a filter. Overlap two and the colours combine; overlap three and they go dark. Children discover subtractive colour mixing this way in about four minutes, without anybody explaining it, and they then spend an hour testing combinations.

It also flattens the play. Light-table work is horizontal, quiet and pattern-based rather than structural, which makes it a good late-afternoon activity when a tower-building session would be too much.

You do not need a light table

• A sunny window is the original version and still the best. Tiles stick to each other and stay put on the glass with a little help from a metal frame.
• A tablet screen on a plain white image, brightness up, laid flat. Free, and instantly available.
• A torch under a sheet of white acrylic propped on two books.
• String lights under a clear storage tub with the lid as the working surface — the standard home-made light table, and it takes ten minutes to assemble.

A purpose-built light panel is worth it only if this becomes a regular activity rather than an occasional one.

Which tiles work

Translucent moulded panels, which is most standard rainbow sets. Opaque themed pieces, printed decals and anything with a solid printed face will not transmit light, so a themed box is the wrong purchase for this. Solid-panel ranges such as TILEBLOX are made for a different job — bold colour and a filled face rather than a window.

If light play is the specific aim, a plain 30-piece rainbow collection gives you the widest range of colours to overlap.

Activities

1. Colour mixing. Predict what blue over yellow will look like, then test it.
2. Stained glass windows. Build a frame of squares and fill it with a pattern.
3. Shadow tracing. Put paper under the tiles in strong sunlight and draw round the coloured shapes.
4. Symmetry with a mirror laid along one edge of the design.
5. Sorting by how much light passes through, which is a surprisingly good introduction to the idea of a scale.

Two practical notes

Keep the light source cool. String lights and LED panels are fine; a desk lamp with a hot bulb pressed against plastic is not, and sustained heat is one of the few things that genuinely damages the magnets inside a tile.

And clean the panels before you start — scuffs and fingerprints that are invisible on the floor are extremely visible when lit from behind. A damp cloth and mild soap, never a dishwasher, as covered in the care guide.