Free Christmas STEM Challenges for KS1 and KS2

December in a primary classroom is busy, noisy and full of glitter. A good STEM challenge turns that energy into proper learning: children plan, build, test and improve, and they barely notice they're doing science. Here are 6 Christmas STEM challenges you can run with paper, tape and things from the recycling box. Each one has a festive story, clear rules, a fair way to test it and the science behind it.

How to run a challenge

1. Ask: read the story and the challenge out loud.
2. Imagine and plan: give teams 5 minutes to sketch an idea before anyone touches the materials.
3. Create: build it, with a timer on the board.
4. Test: test every design the same way so it's fair.
5. Improve: give 5 more minutes to make one change, then test again.

Teams of 3 or 4 work best. An adult should supervise every challenge, especially anything with scissors, drops from a height or small parts.

6 Christmas STEM challenges

The Tallest Tree

Structures · 30 minutes · KS1 + KS2

The elves have lost the Christmas tree for the school hall. Can you build a new one? Build the tallest Christmas tree that stands up on its own.

Rules:

• Use only the materials listed.
• It must stand for 10 seconds without being held.
• It must look like a tree!

You need: 10 sheets of A4 paper, 1 metre of sticky tape, Scissors, Ruler or tape measure.

Test it: Measure from the table to the top in cm. The tallest tree that stays standing wins.

Extra challenge: Can your tree hold a paper star on top without falling over?

The science bit: Rolled tubes and cones are much stronger than flat paper, and a wide base keeps a tall shape steady.

Teacher tip: Show a flat sheet flopping, then roll it into a tube so it stands. Ask: which shape is strongest?

Snowflake Symmetry

Maths · 20 minutes · KS1 + KS2

Real snowflakes have six points and are symmetrical. Can you make a perfect one? Fold and cut a paper snowflake with 6 points and as many lines of symmetry as you can.

Rules:

• Start with a square of paper.
• Fold first, then cut.
• Count the lines of symmetry when you open it.

You need: Square paper (thin paper is best), Scissors, Pencil, A small mirror, if you have one.

Test it: Use a mirror or fold it to check each line of symmetry. How many did you find?

Extra challenge: Make one with 4 points and one with 8. Which has more lines of symmetry?

The science bit: Snowflakes grow from tiny ice crystals. Water joins in a six-sided pattern, so most snowflakes have six points.

Teacher tip: Fold the square in half to make a triangle, then fold it into three equal parts to get 6 points.

The Elf Parachute

Forces · 30 minutes · KS2

An elf has to jump from the sleigh with a present. Design a parachute that floats down gently. Make a parachute that carries a small elf (a peg or 5 paper clips) to the ground as slowly as possible.

Rules:

• Drop it from the same height every time.
• The elf must stay attached.
• You can change the size and shape of the canopy.

You need: Plastic bag, tissue paper or bin bag, String or thread, Sticky tape, A peg or 5 paper clips, Stopwatch.

Test it: A grown-up drops it from about 2 m. Time the fall. Do 3 drops and write down the best.

Extra challenge: Does a bigger canopy always fall more slowly? Test 3 sizes.

The science bit: Air resistance pushes up against the canopy as it falls. A bigger canopy catches more air, so it falls more slowly.

Teacher tip: A grown-up does the high drop while children time it. Mark the drop spot with tape so it is the same each time.

Keep the Snowman Cold

Materials · 45 minutes · KS2

A snowman is going on holiday somewhere warm. Can you stop him melting on the way? Wrap an ice cube (your snowman) so it takes as long as possible to melt.

Rules:

• Everyone gets the same size ice cube at the same time.
• Your wrapping must fit in a paper cup.
• Check it every 15 minutes.

You need: Ice cubes the same size, Paper cups, Foil, cotton wool, fabric, newspaper, packing material, Tape, Timer.

Test it: Check every 15 minutes. The last snowman to melt wins. Keep one ice cube unwrapped to compare.

Extra challenge: Which material was the best insulator? Put them in order from best to worst.

The science bit: Insulators slow down heat moving from the warm air into the ice. Materials that trap air, like cotton wool, work well.

Teacher tip: Use same-size cubes from one tray and start everyone together. Teams can try another challenge while they wait.

Christmas Shadow Show

Light · 40 minutes · KS1 + KS2

The power is out at the North Pole, but the show must go on! Put on a Christmas shadow puppet show. Make 3 Christmas shadow puppets and use a torch to tell a short story.

Rules:

• Cut the puppets from card and tape them to sticks.
• Make one shadow that is big and one that is small.
• Your story needs a beginning, middle and end.

You need: Card, Scissors, Lolly sticks or straws, Tape, A torch, A white wall or sheet.

Test it: Hold a puppet close to the torch, then further away. Measure the shadow each time.

Extra challenge: Can you make a coloured shadow with tissue paper?

The science bit: Light travels in straight lines. Card blocks the light and makes a shadow. The closer the puppet is to the torch, the bigger the shadow.

Teacher tip: Darken the room as much as you can. Each team can perform for the class.

Jingle Instruments

Sound · 40 minutes · KS2

The elf band has lost its instruments, and the Christmas concert is tonight! Make an instrument from recycled things that can play at least 3 different notes.

Rules:

• You can pluck, blow, tap or shake it.
• It must play a high note and a low note.
• Practise a short tune to play to the class.

You need: Boxes and elastic bands, Paper cups and straws, Bottles or glasses and water, Rice or dried pasta, Scissors and tape.

Test it: Play a high, a middle and a low note. Can your class guess which is which with eyes closed?

Extra challenge: Line up 4 bottles with different amounts of water and tap them gently. Which is the highest note?

The science bit: Sounds are made by vibrations. Shorter, tighter or thinner things vibrate faster and make higher notes.

Teacher tip: Tapped bottles: the one with the least water is highest. Blown across the top: the one with the most water is highest.

More challenge ideas

The full pack has 24 challenges, one for every day of Advent. The other 18 are: The Reindeer Bridge, The Sleigh Slide, Snowball Catapult, Paper Chain Champion, The Foil Sleigh Boat, The Present Zip Wire, Static Snow, Bauble Balance, Gingerbread House Blizzard, The Rocket Reindeer, Wrap It Up, Light Up the Star, The Sleigh Run Marble Race, The Strongest Stocking, Code Santa's Route, The Spinning Top, The Bauble Drop, Santa's Sleigh Machine.