This simple Santa STEM challenge involves building different boats for Santa to cross a river. Children can experiment with different materials, shapes, and sizes of boats to find the best one.
Oh No! Santa’s sleigh has broken down, and he needs to cross a river.
Build two different kinds of Christmas boats that will float and hold the weight of some decorative bells or other Christmas trinkets.
Materials
- Lolly sticks
- Jam jar lids
- Cardboard
- Small boxes or paper cups
- Scissors
- Sponges
- Water tray
- Small objects to add.
Instructions
Construct your boats. Don’t be limited to the materials above: use corks, egg cartons, half an orange, or anything else you think might float.
Test your boats by placing them into a container of water.
Don’t worry if the boats sink. That’s all part of the fun.
Questions to ask
Did any of the boats sink? Is there anything you could add to the boat to help it float?
Do all the boats float? What happens when you add the Christmas items?
Which materials are the most waterproof?
How much weight can you add before the boat sinks?
Does it matter where in the boat you put the extra weight?
Does it make a difference if the water is deeper?
What do you notice about materials that float? Do they have any properties in common?
Boat for Santa STEM Challenge FREE Printable Worksheet
Add some structure to your challenge with my FREE worksheet!
Why does this happen?
Whether an object sinks or floats depends on its density.
Density is how tightly packed the material inside an object is. Heavy objects do not always sink. For example, ships are heavy but not very dense, so they float.
Extension Ideas
Playtivitities has some brilliant ideas for making boats from recycled items.
Try to build a bigger boat that will hold a Santa or reindeer figure.
Can you build a boat using four different materials, one of which you know sinks?
Try one of my easy Santa STEM challenges!
Make a Mini Science Kit
We made a cute mini science kit containing a red sponge, a red lolly stick and paper for a sail. This would make a great little activity to give to friends.
What do you think of our Christmas boats? What will you use to build yours?
Last Updated on December 12, 2025 by Emma Vanstone
