What you鈥檒l need

From nature:

  • Assorted leaves and twigs

From home:

  • String
  • Clothespins or paper clips
  • Paper
  • Coloring pencils or felt-tipped pens
  • Optional: two chairs

How to do it

1. Go outdoors and collect a variety of leaves and twigs.

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2. Stretch out a piece of string (between two chair legs or across the window, for example) so the sun can shine on it.

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3. Hang the leaves on the string with clothespins or paper clips so the sun casts the shadow of the leaves onto your sheet of paper.

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4. Draw the outlines of the leaves and then color them in.

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Topsy鈥檚 tip

  • Examine your leaves and branches for color, shape, thickness, structure, size, resistance to tearing, and the like. What do you notice?
  • Leave your chain of leaves and your drawing in the same spot for a day. Look closely at the different shadows: How do they change throughout the day? When are the shadows the longest?
  • Prepare a quiz and let your friends and family guess the type of leaves based on the shadows cast.

Learn with Topsy

  • When examining your leaf shadows, have you noticed the many different shapes nature has given to leaves? No one leaf is like the other 鈥 each is unique.
    When you see a leaf lying on the ground, do you know which tree it fell from? Can you name the tree? Maybe you have a favorite tree in the garden and recognize its leaves, even when you find them somewhere else? You鈥檝e probably noticed that leaves take different shapes, and sometimes a shape is so distinctive that we remember it.
  • But why so many different shapes? That鈥檚 not easy to answer. What we do know is that plants adapt to their environment. The leaves of a plant in the desert are generally small and thick, waxy or prickly to better retain moisture. In the rainforest, by contrast, they are often narrow, thin, long, and tapered, so that large volumes of rain can trickle off them easily, and the plant doesn鈥檛 drown in water. However, if that鈥檚 all there were to it, all the leaves in Switzerland would look the same. But that鈥檚 not the case. This is because plants have been around for over 400 million years. And every single species has evolved differently: In the north, plants protect themselves against the cold, but in the south, they protect themselves against the heat. They try to defend themselves against animals (e.g., with their thorns) or to get animals to live on them to help them (e.g., ladybugs). Each plant wants something else from nature and has evolved its shape in whatever way is ideal for it. But all leaves around the world have one thing in common: they transform light into life. This transformation process is called photosynthesis, and it converts light, carbon dioxide and water in the leaves of plants into glucose and oxygen for breathing, making life on Earth possible for all living beings.