One of my favourite lessons looks at why boats float. Being located near the historic port of Portsmouth, my class - aged 9-10 - has a real interest in and experience of this subject. The lesson is also a practical one that they very much enjoy, with a good mix of child-led and teacher-led tasks.

I start by giving the children a range of objects and a large tub of water. They have 10 minutes to discover which items float and which sink. As each object is pitched into the water, I ask the students to explain the reasons behind its fate. They tend to offer a range of interesting explanations, before I get them to test their theories with similar objects.

This provides the basis for the next stage of the lesson. We discuss the common features of the floating objects in the experiment. After a conclusion is reached - and the children have always worked out that air is a key component - we move on to testing a big ball and a small ball in the water. By pressing down on these balls, the children are introduced to the concepts of water resistance and displacement of water. We’re now ready to apply our learning to boat-building.

The children work in groups to find the best shape for a boat, testing their theories and using Multilink cubes to weigh the “boats”. My class becomes a hub of scientific experiment, with successes and disasters at sea in equal measure.

This is always my favourite science lesson as the children are engaged, asking questions and giving reasons for their answers, generating their own scientific experiments and ideas, and using scientific language through play and exploration. Of course, it’s great fun, too.

Gianina Severs teaches at Sharps Copse Primary School in Hampshire in the South of England.