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Notes from the field ·

Which Hat Keeps the Sun Off? A Light, Colour and Heat Test for K–2

By Ahmed, founder

On a sunny day, children are told to wear a hat. This activity asks them to find out which hat material works best, and the answer has two parts: what blocks light, and what gets hot.

What you need

  • Squares of dark cloth, light cloth, paper, aluminium foil and card, all the same size
  • A sunny spot or a bright lamp
  • A white sheet of paper for shadows
  • A thermometer (optional)

Part 1: which gets warmest?

  1. Predict. Which square will feel warmest after 10 minutes in the sun?
  2. Lay all the squares on a table or pavement in direct sunshine, side by side.
  3. After 10 minutes, ask children to place a hand on each (not too long) and describe how warm each feels. With a thermometer, place its bulb under each square and record the temperature.
  4. Rank from warmest to coolest.

What usually happens: the dark cloth gets warmest, and the light cloth and foil stay cooler, because dark surfaces absorb more sunlight and light or shiny ones reflect more.

Part 2: which makes the darkest shadow?

  1. Hold each material up in the sun or in front of a lamp, so that its shadow falls on white paper.
  2. Compare: which shadow is darkest? Which lets some light through?

Foil and card block almost all the light. Thin cloth and paper let some through, so their shadows are paler.

Put it together

A good sun hat should block light (dark shadow) and not heat up too much (light colour). Ask children to design a hat using what they learned: “light-coloured cloth with a wide brim,” for example.

Real hats also need to be comfortable, breathable and, for protection against ultraviolet rays, made from fabric designed for it. Colour and shadow tests don’t measure that, so tell children plainly that their tests are about heat and light, and that sunscreen and shade matter, too.

Other properties

Stretch, bend and feel each material. Which would be good for a hat? A coat? A roof? Properties decide the job.

Safety

Never look at the Sun. Don’t leave hands on hot surfaces. Use hot pavement carefully and check it before touching.

The full lesson is Which hat keeps the sun off? in Test It, Choose It: Materials. Sign up for three lessons free.