3. Building Models of cells
One way of helping your students to visualise things like cells (or viruses or molecules) is to let them build models. Resource 6 explains some of the advantages of using models in science. A resourceful science teacher will collect materials such as cardboard packets, plastic, packaging materials, wood and clay so that when they wish to build models, they have materials the students can use. You could also ask your students to collect materials and keep them in a cardboard box in your classroom. When students see cells in diagrams or on microscope slides, it is quite difficult for them to imagine the cells in 3D. You should encourage them to think about materials that will best represent their ideas of what a cell is like. Getting them to plan and deliver a presentation about their model means that they will have to clarify their own thoughts and explain them to others. Our understanding of abstract concepts is closely linked to our ability to use language to order our thoughts about them. While there are advantages in asking students to present to the whole class, this can take a lot of time and many of the benefits are just as great if they do the presentation to a partner.
Case study 3: Making and assessing models
Mrs Muthui had been teaching for 2 years. When she was at college her tutor had encouraged her to use models with her students. Last year her students made models of cells, but Mrs Muthui did not think it had worked very well. The students did not really understand what she was looking for. So this year, she did it differently. She showed her students some of the ones that she had saved from last year. She asked them which one they thought was the best and to explain why. Together, they made a list of marking criteria for the models. She then gave the class two weeks to make a model, working in groups of two or three, and was delighted to find them in the classroom before and after school, working on their ideas. She organised a display and asked her students to mark each others’ models. She invited the head of department and the headteacher to see the display. Everyone was talking about it and some of the other teachers came to see as well. Mrs Muthui was delighted. The models were much more creative and imaginative than last year and she realised that sharing the marking criteria with the students had helped them to understand what was expected of them. She began to do this more often and gradually found that the students took more responsibility for their own learning.
You can see the criteria in Resource 5 – but don’t just use those, make up some of your own.
Activity 3: Making and presenting models
In teaching about cells, you will have introduced your students to cells that are adapted to a particular function, and you will have encouraged them to draw diagrams of the cells in their notebooks. Ask them to make a 3D model of one of the cells they have learned about. Give them materials such as cardboard, water, clay, wool, plastic drinks bottles, plastic bags or yoghurt pots, but also encourage them to use any other available materials.
When they have made their models, ask them to prepare a spoken presentation on the model. They should explain the structure of their cell and how it is adapted to its function. Encourage them to point out any aspects of the real cell which they could not show accurately on their model. They should all get the chance to work in pairs, giving their presentation to their partner. If you have time, you could choose the best models and ask those students to make a presentation to the whole class.
2. How big are cells?
Resource 1: Background information on cells