This set of activities enables students to directly observe how everyday objects behave in water and to investigate the factors that determine whether an object will float or sink. Through play and exploration, students are supported to predict, observe and make sense of their observations.
The activities build upon each other to encourage students to make more detailed and refined observations and provide multiple opportunities for exploration and discussion. The article Building Science Concepts: Floating and sinking has useful background information for educators.
By the end of this activity, students should be able to:
- make predictions about whether a range of objects will float or sink
- discuss where the objects are in the water – for example, on top or partially submerged
- make observations that may contribute to understanding why the items float or sink
- classify/group items on the basis of similarities in their ability to float or sink
- design their own investigation to answer a question they have regarding floating and sinking (optional).
Download the Word file (see link below).
Related content
The article Building Science Concepts: Floating and sinking has useful background information for educators.
The article Water density has information about ice and floating.
The level 4 Connected article A sinking feeling introduces the science concepts underpinning floating and sinking in the context of a boat race.
The PLD article Physical World – Floating and sinking curates Hub resources on this topic.
Our Floating and sinking Pinterest board is full of related resources.
Activity ideas
Will this float or sink? uses an interactive or paper-based graphic organiser to consider whether an object floats or sinks. Use it prior to a unit on floating and sinking to gauge students’ thinking and again during and after the unit as formative assessment.
Floating and sinking – exploring forces use play and exploration to explore the support force (upthrust) that keeps objects afloat.
Explore buoyancy in water by making a Cartesian diver.
Investigate water density by floating eggs in freshwater and saltwater.
Useful links
Related Building Science Concepts books
- Floating and Sinking: How Objects Behave in Water (Book 37) – explores floating and sinking in water. This is aimed at levels 1–2.
- Understanding Buoyancy: Why Objects Float or Sink (Book 38) – explores floating and sinking including in other media. This is aimed at levels 3–4.
