Some times I meet people who are surprised when I suggest that all aspects of maths can be taught outdoors. After all, money and playing in a natural space do not obviously go hand-in-hand the way that perhaps it would with a role play area about a train station.

Honesty or Lunaria annua is one of my favourite plants because it's beautiful seed heads are one of winter's wonders. As a child I adored the translucent paper thin head and the seeds tucked in between the thin flat pods. It is the seeds that are the "money". In the right garden, a child could become very rich. I rather like the potential for the seeds to become fairy money or nature's money.

On a cold and frosty day, it is perfect weather for a winter walk. Often the air is still, the sky bright and the colours of the earth simply glow. Take a magnifying glass or fresnel lens and just enjoy looking at the frosty "jewels" decorating the plants.

For older children, working out how this hoarfrost was created is an interesting challenge. Essentially it's frozen water that's taken on a crystal form. Water vapour in the atmosphere has frozen onto the colder plant surface.

Altogether quite remarkable.