How many coins to sink a boat?

Today’s STEM Challenge is super simple. The aim is to find out how many coins it takes to sink a foil boat.

First, we cleaned up our treasure, then we made different sizes of kitchen foil boats and tried to sink them!

If you want to extend the pirate theme, we love making treasure maps with cold tea and coffee, too!

How to clean coins

To clean your coins, just put them in vinegar for a couple of hours and they’ll soon be super shiny! If you want to turn this into more of an investigation there are a few other coin cleaning methods you could try.

Scrub the coins with a baking soda paste ( make this by mixing a little water with baking soda )

Soak in lemon Juice

Soak in a fizzy drink – don’t drink the fizzy drink afterwards!

soak in salt and vinegar.

Coins cleaned with vinegar. 3 shiny and one that hasn't been cleaned.

Sink the Boats STEM Challenge

You’ll need

Tin foil

Coins

Towel to dry the coins

Instructions

Construct a boat with kitchen foil.

Image of a boat made from aluminium foil with a playmobil person inside

Check the boat floats.

Once you’re happy the boat floats, add coins slowly to find out how many coins it takes to make the boat sink.

For the first attempt, try spreading the coins out, and then try again, but place all the coins at one end.

tinfoil boat with a toy figure and coins inside

Remember to make sure the coins are dry for each boat you test.

Boat STEM Challenge Extension Tasks

Repeat the investigation, but this time use different sized foil boats. Do smaller boats sink with less coins?

Make boats from recycled materials and work out how much weight it takes to make each one sink.

boats made from recycled material and lemon skin — Mini boats for a science challenge

What makes an object float?

Things float if they are less dense than the liquid they are in ( in this case water ). If they are more dense, they sink.

Adding coins to the boats increased the density of the boat. When the density of the coins and boat is greater than the water the boat sinks.

More STEM Challenges for Kids

These printable STEM Challenge cards contain 12 fun and super simple STEM challenges for kids, including building rafts, super long paper chains and fizzy potions.