STEM floating snowmen and Christmas trees

by Fellowship Agency July 25, 2018

A festive buoyancy and balancing STEAM challenge using your Christmas themed tinker trays.

Can you make a snowman or mini Christmas tree that will float upright on the water? Test if they sink or float and if they stay upright. Have fun and be as festive as you can when decorating! This activity works best when done with friends or classmates.

You will need:

  • 2 x shallow Gratnells (F1) trays with inserts for organisation (use red or green trays if you want to be as festive as possible)
  • 1 x Gratnells A3 tray half filled with water
  • Polystyrene balls (different sizes)
  • Ping pong balls
  • Pine cones with frosted tips (mini Christmas trees)
  • Cocktail sticks
  • Bottle tops
  • Lolly pop sticks
  • Sellotape
  • Pipe cleaners in festive colours
  • Corks
  • Googly eyes
  • Scissors
  • Felt tip pens
  • Bottle tops
  • Jingle bells
  • Tinsel or Lametta
  • Elastic bands
  • Any other festive decorative items that take your fancy!

What to do:

Use any or all of the equipment in the trays to make a snowman or miniature Christmas tree that will float upright when placed on the water.

What is happening?

Water pushes upwards with a force called ‘upthrust’. You can feel upthurst if you try to push a light object such as a balloon under water. If the weight of an object placed on the water is equal to or less than the force of the upthrust then it floats. When something floats we say it is buoyant. The shape, design, materials and construction of your snowmen and Christmas trees determine their buoyancy. If the weight of the snowman or Christmas tree is greater than the force of the upthrust then it will sink.

This activity also tests your balancing skills. The weight of your snowman or Christmas tree must be evenly distributed or it will topple over on the water. This is because of stability, and the effect of gravity on the object. The best chance of creating something that will balance, and stay upright in the water, is to keep the bulk of the weight low down and maintain a low centre of gravity. Something top heavy, or with uneven weight distribution, will topple over much more easily. To learn more about balancing and centre of gravity take a look at this great explanation by Explain That Stuff.

Other things to try……

  • Once your festive creations are floating and balanced on the water can you race them? Blow gently and see if they will sail from one side of the tray to the other. Which one is the quickest? Did any topple over?
  • Discuss the differences in your designs, why were some of the snowmen and mini Christmas tree more successful at sailing across the tray than others?
  • Modify your design or build a new snowman or mini Christmas tree based on your observations. 

Health & Safety

As with all Gratnells Learning Rooms What’s In My Tray Activities, you should carry out your own risk assessment prior to undertaking any of the activities with children.