Worksheets and lesson ideas to challenge students aged 11 to 16 to think hard about diffusion (GCSE and Key Stage 3)
Where to start?
Start the lesson by frying some food at the front of the class. This should definitely stimulate some interest and get students thinking about particles mixing, and moving randomly from one place to another.
There are some great demonstrations to observe diffusion. Give students a stop clock and ask them to record when they first smell deodorant that has been sprayed in the middle of the class. If you also get students to raise their hands when they first smell the deodorant you will get a lovely ‘ mexican wave’ effect. I used to do this demo standing at the front of the class, but this introduces the misconception that particles move in one direction. Try adding lead nitrate and potassium iodide to a Petri dish of water, yellow lead iodide will form – this provides a great starting point for introducing the idea that particle size affects the rate of diffusion.
Measuring the rate of diffusion
GCSE practical to investigate how the rate of diffusion is affected by temperature. Students measure the rate of diffusion of food dye at different temperatures. Students also apply their understanding of diffusion and temperature to gas exchange in cold-water worms. (PDF)
Factors affecting the rate of diffusion
Key Stage 3 worksheet on factors that effect the rate of diffusion. In this activity, students put a series of particle pictures in order of diffusion rate. The idea of this task is that it (hopefully!) will illicit the idea that the rate of diffusion depends on temperature and particle size. (PDF)
- Why don’t all particles at the same temperature diffuse at the same rate?
- Is diffusion the same as mixing? Explain your answer.
- How is the spread of fire through a forest similar and different to the diffusion of partciles?
- Particle pictures and the particle model
- Elements mixtures and compounds
- Separating techniques