Treasure Island Multiplication

by Kim O'Brien
(London, UK)

My colleague and I wanted to plan an exciting lesson for our Year 3 classes involving investigative skills and getting to grips with a multiplication square.

We had introduced multiplication squares the day before so the children had some practice with them and knew how they worked.

We started off the investigation by reading them a story about Year 3 being on a trip on a treasure island. They had found the pirates' treasure and the pirates were now after them.

We showed them a map of the island which had a 10 x 10 grid over it with some of the lines of multiplications filled in, but most blank. They had to work out a path from their position by the treasure to a boat on the other side of the island by filling in blank squares on this multiplication grid.

To make sure it wasn't too easy (ie. too little work) for them, we told them they could not choose a diagonal path. The squares had to be touching on the sides, not diagonally.

At the end of the lesson, we sat the children on the carpet (or the boat!) and all rowed away from the island together, chanting the 3 x table to the beat of a drum.

The children completed their task in pairs and in advance of the lesson we had prepared enough shoe boxes for each pair containing a bag of Dienes cubes, a number line, a hundred square, scrap paper and pencils for them to use as they chose.

There was also a sealed "Top Secret" envelope containing a completed multiplication square, which we told them they could open in a dire emergency. We told them that every child who managed to resist the temptation to open this envelope would receive a confidence merit - no one opened it!

We differentiated the task by giving the lowest ability smaller grids and only 2x, 3x and 10x to work out. The middle ability had more squares filled in on their grids than the higher ability group.

As an extension we had available small multiplication grids with titles such as "Extra water for the journey" home. The children needed to use division to work these out, as we had provided answers in the middle of the square, but not all the (jumbled up) numbers around the sides.

The children loved this lesson and really had to use their investigative skills to succeed. It was also an excellent way for us to observe how they tackled the task and spot any gaps in their knowledge.