Spinning seeds

The pavements around our house have been sprinkled in ‘paper snow’ over the past few weeks. Well they were until it rained this week and now it’s all turned into mulch. We had a lot of fun playing with it while it was dry, mainly scooping it up and throwing it over each other. The paper snow was in fact seeds from the elm trees that line the streets where we live (which we thought were lime trees so we have learnt something new!). So we have been talking about seeds and how they travel. They can hitch-hike, float, be fired into the air and fly. This little activity is a good way to look at how some seeds fly, in particular sycamore or helicopter seeds.

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What you need:

  • Paper (essential – any old paper will do as long as you can cut a rectangle out of it).
  • Scissors (essential – for cutting).
  • Paperclips (essential – one per helicopter).
  • Colouring pens/pencils/crayons (optional – if you want the kids to colour them in for an extra activity).

What to do:

  • Cut a rectangle out of the paper, twice as long as it is wide.
  • Half way down the long side cut in about a third of the way on both sides.
  • On the bottom half fold in both sides and then fold the bottom up and secure with a paperclip (see photos).
  • Cut a slit in the top part just over a third of the way down. Then bend the two top strips, one forward and one back (again see photos, it’s hard to explain but very easy to do!).
  • Hold up high and let go!

Tips/extra bits:

  • If getting kids to colour then probably easier to do before all the cutting and folding.
  • Try making different size helicopters. My inquisitive husband made some with longer wings after he saw ours. We then got the kids to guess which ones would hit the floor first. The ones with the longer wings should be slower to hit the ground.
  • Bend the wings in different direction on a couple. They will spin in opposite directions. Again you can get the kids to predict what will happen.
  • See if you can find a sycamore tree, and watch some seeds spinning as they fall if you are lucky! Otherwise just try and find some seeds on the ground and throw them up in the air to watch them spin.

(No need to be semi naked or in your pyjamas to perform this activity, we just were!)

The science bit

When the helicopter falls air pushes against the wings. Due to the design of the helicopter the wings are pushed in opposite directions, making it spin. A sycamore seed works in the same way, and spins in the air as it falls from the tree. Spinning enables it to stay airborne longer, and therefore potentially travel further. The tree wants it’s seeds to be dispersed far away from itself. This reduces competition for resources (space, food, light) and helps the species cover a larger area. This is a bit of a back up in case of emergency (i.e. something destroys one area of land).

Explaining it to children

Seeds want to travel far away from the tree so that they find a good place to land, giving them their own space to grow. The helicopter style wings of a sycamore tree (which are a bit like the helicopter that you make) help the seed stay in the air for longer, so it can travel further. The air is pushing the wings of the seed/helicopter, which makes it spin. Think of of it like a roundabout in the park, you have to push the sides of that to make it spin.

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Experiment based on an activity from the fantastic Usborne Activities: 365 Science Activities book.

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