Worksheets and lesson ideas to challenge students aged 11 to 16 to think hard about osmosis and osmoregulation (GCSE and Key Stage 3)
Where to start?
GCSE thought experiment about osmosis. Use this thinking task to get students to engage with the process of osmosis. This could be used at the start of the topic to challenge and motivate students to solve a problem. Whilst students may not arrive at the right answer, it will focus their thinking on the parts of the problem i.e. membrane, solute and water, making any explanations that follow more relevant and likely to stick. (PDF)
Two of my favourite ways to observe osmosis are the naked egg experiment and using gummy bears. For the naked egg experiment, place some uncooked eggs in vinegar overnight – this will remove the shell. Then place one egg in water and the other egg in a concentrated salt solution (8%) for 24 hours. Remove the eggs and observe what has happened. With the gummy bears (remember the theme tune!) just place them into different salt solutions and get students to observe what happens after 24hours. You can get them to take measurements before and after e.g. mass and length and calculate some percentage changes.
Compare the isotonic point of sweet potato with white potato by placing potato disks in different concentrations of NaCl solution. Plot a graph of % change in mass versus concentration.
GCSE diagnostic multiple choice questions on osmosis. Students work individually on each diagnostic multiple choice question and then discuss answers in pairs. Or, each question can be used within your existing lessons to check for understanding. Answers are in the notes section of the PPT file. It’s worthing checking out the further reading below on osmosis misconceptions – I think we teach most of them! (PDF)
Hypertonic, hypotonic and isotonic solutions and the effects of osmosis
GSCE worksheet on hypertonic, hypotonic and isotonic solutions. A simple context is set-up using a nurse who administers the wrong IV drip. This activity could be used to consolidate understanding around osmosis and the effects of hypotonic and hypertonic solutions on cells. (PDF)
Osmosis and osmoregulation in context
GCSE activity looking at how osmosis affects freshwater and marine organisms. Students work in small groups to apply their understanding of osmosis to explain different adaptations in marine and freshwater organisms. This activity requires students to have a good understanding of the principles of osmosis so they can apply their knowledge to new situations. (PDF)
- Why does osmosis require a membrane?
- Suggest how the ‘antifreeze’ enables the wood frog to survive winter.
Kosinski, R. J.; C. K. Morlok (2008). Challenging misconceptions about osmosis. Association for Biology Laboratory Education. 30: 63–87