Handout 4.3. Give out Handout 4.3. Use it to explain how participants can use models to teach cells.

Transcription

1 Handout 4.3 Using models to teach about cells Give out Handout 4.3. Use it to explain how participants can use models to teach cells. 10 minutes

2 Make the following points: The QCA scheme of work invites teachers to use models to teach cells, such as in Units 7A and 8A. Research has shown that the choice of materials in making model cells is important and can lead to misconceptions. For instance, the use of wallpaper paste in animal cell models can contain air bubbles. These bubbles have subsequently been drawn by pupils who think that all cells contain them (vacuoles in plant cells are not randomly generated like air bubbles). It is important for teachers to discuss with pupils what each part of the model represents. It is equally important to discuss the strengths and weaknesses of the model; this is something that is not always done you might like to stress the importance of this. Cells will be a new area of the curriculum for pupils at Key Stage 3; they often have difficulty recognising that animals and plants are multicellular organisms and that cells are three-dimensional. Many teachers introduce cells using three-dimensional models. The QCA scheme of work does this in Unit 7A. Slide 4.4 Slide 4.5 Slide 4.6 Research has shown that if this modelling of cells is continued, so that pupils model specialised cells and build tissue and organs from model cells, they make even better progress. Use Slides 4.4, 4.5 and 4.6 to show some models that pupils have made. Models of typical animal and plant cell Slide Misconceptions in Key Stage 3 science notes for course tutors Crown copyright 2002

3 Specialised cells pupils models Spermatozoa Nerve Cell Slide 4.5 Cells arranged as tissue in a tank Slide 4.6 Handout 4.7 Refer participants to Handout 4.7. Say that: When teaching cells we can adopt a similar approach to that of teaching particles, by increasing the sophistication of the teaching model step by step. Additional guidance It would be useful if you had some model cells prepared to demonstrate what can be produced. Unfortunately there is no time available in this unit to allow participants to make their own, but by having some already made you could provide useful examples of how they could do this in their own schools. A model of many cells forming a model tissue could also be demonstrated. 34 Misconceptions in Key Stage 3 science notes for course tutors Crown copyright 2002

4 Reference Models and modelling project 2001 (Hampshire LEA, Southampton LEA and the University of Reading)

5 An approach to teaching Handout 4.3 cells using models Build three-dimensional models of typical plant and animal cells Discuss what each part represents, developing specific language Discuss strengths and weaknesses of any model and how each may be improved Ask pupils to build their own models of specialised cells, identifying any strengths and weakness Build a model tissue from model cells as a class Relate the model to what is seen through a microscope Consider how you might construct some model organs from model tissue, e.g. leaf, heart, eye 36 Misconceptions in Key Stage 3 science notes for course tutors Crown copyright 2002

6 Developing a sequence of good enough cell models Handout 4.7 Scientific idea The cell is the basic building block of living material, consisting of nucleus, cytoplasm and membrane Plant cells also have a cell wall and vacuole Cells are adapted to their function and have specialised forms Tissue is composed of groups of the same type of cells and different tissues can form organs The cell membrane is differentially permeable Nucleus contains genetic material and can divide causing cell division Teaching model Plastic bag filled with water or jelly and a table tennis ball Plastic bag filled with wallpaper paste (shows vacuole) placed in jar (shows cell wall) Different materials can be used to show how cells are specialised and adapted to their function such as balloons for guard cells, football for egg and marble with tail for sperm (to show relative size) Plastic bag cells placed in fish tank to show tissue; compare this with looking down the microscope to see layers Visking tubing and particle-sieve models Nucleus made of jumble of pipe cleaners, animations Can be used to explain All living things have similar structures Differences between plant and animal cells Differences in cell form reflect their functions Tissue under the microscope contains many cells that are the same Gas exchange in the lungs, respiration, digestion, water uptake in root hair, photosynthesis Reproduction and growth 37 Misconceptions in Key Stage 3 science notes for course tutors Crown copyright 2002