Following on from their sink or float experiment yesterday, I challenged them to make boats for their Blaze characters.


  • Recycling: plastic containers and trays, wooden trays, cardboard trays and tins
  • Sticks for masts
  • Paper for sails
  • Scissors
  • Sticky tape
  • Felt tip pens


Making boats

They selected the containers that they each wanted to use as the hull for four of their boats. I encouraged them to use different sized containers, made of different materials, to make the experiment more interesting.

Deep in concentration.

Ioan cut out a flag from pink and blue paper, then stuck it around a stick, to make a flag pole. Finally, he stuck the flag pole to his boat.

Finny used orange and yellow paper to make his flags. He chose to attach his flag pole to the boat before sticking the flag on.

Finishing off their remaining boats. Ioan made sure all his flags were colour coordinated, meanwhile, Finn wrote the name of each character on their flag.

Their finished boats ready to be tested.

Finny testing buoyancy

Boat 1

Boat 2

Boat 3

Boat 4

Ioan testing buoyancy

Boat 1

Boat 2

Boat 3

Boat 4

The pictures above, show the tuna can floating without Blaze inside, then having sunk after carrying Blaze.

What is buoyancy?

When something is in water, there are two forces acting on it.

Things that float are buoyant. An object floats when the weight force on the object is balanced by the upthrust (upward push) of the water on the object. The upthrust of the water increases with the volume of the object that is under water; it is not affected by the depth of the water or the amount of water.

If the weight force down is larger than the upward push of the water on the object then the object will sink. If the reverse is true then the object will rise.

Rising is the opposite of sinking.

A buoy has lots of air in it, making it less dense than the sea around it so it floats. An anchor has much less air in it and is much more dense than the water, so it sinks.

Coin and cereal box experiment

In this experiment, the cereal box and the coin were the same weight.

The weight of the cereal box was spread over a wider surface area, increasing the upthrust of the water. As the cereal box was less dense than the water, it floated.

Although the coin was the same weight, that weight was distributed over a much smaller surface area, so there was less upthrust from the water. The coin was more dense than the water, which made the coin sink.

DfES Outcomes for EYFS and National Curriculum (2013)

Science Year 1 programme of study

Everyday Materials

  • distinguish between an object and the material from which it is made
  • identify and name a variety of everyday materials, including wood, plastic, glass, metal, water, and rock
  • describe the simple physical properties of a variety of everyday materials
  • compare and group together a variety of everyday materials on the basis of their simple physical properties.

Art and design

Key Stage 1 Programme of study

  • use a range of materials creatively to design and make products
  • use drawing, painting and sculpture to develop and share their ideas, experiences and imagination
  • develop a wide range of art and design techniques in using colour, pattern, texture, line, shape, form and space