Pebble creature problem solving & estimation

July 18, 2018

How many pebble creatures will sink the boat?!

6 pebble creatures floating in a milk carton boat
Author: Muddy Faces

Age Range: all ages

Duration: 1-2 hours

Location: anywhere

Time Of Day: any time

Season: any

Tags: boat, displacement, estimation, numeracy, pebbles/stones, water

Category: curriculum outdoors


Create some pebble creatures – acrylic pen eyes are best for this activity.

Plan the session to be child led play and learning, this makes learning relative and is best achieved by adults standing back and observing.

Important note

If using sticky eyes in your outdoor setting use paper ones rather than plastic.
Paper sticky eyes are white so you can see them on the ground if they fall off, thus helping with a ‘leave no trace’ approach to being outdoors.
Plastic googly eyes are best left at home as, if lost and left behind, they can have a detrimental impact on the environment.

drawing eyes onto a pebble with black acrylic pen

Make a vessel – how about using some items heading for the recycling bin?

Boats can be all sorts of shapes and sizes and made of different materials. The one pictured is made from an old milk carton.

milk carton boat

The children are now leading the play

There are endless learning opportunities taking place, with the added benefit of time spent with one of the elements. In addition playing with water is calming and therapeutic.

One pebble creature floating in a milk carton boar

Do they:

count how many pebbles the boat will carry?

have discussions about what will happen?

come up with design improvements?

estimate how many creatures the boats will hold?


test theories?


five pebble creatures in a milk carton boat