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Practical work and subject knowledge

As teachers we spend a large proportion of our time in lessons on practical activities, because we know that good quality practical work can engage students and help them to develop their understanding of concepts.

Practical work supports the building of links between what our students see and physically do, and the scientific ideas behind their observations.

So far this week we have considered progression in skills but we also need to consider the progression in conceptual understanding that students need to have developed to be able to explain what they are observing.


If our students develop good microscope skills and are able to produce good slides of the red outer skin of rhubarb, they can use these to observe the effects of osmosis on cells and see the process of plasmolysis after concentrated salt solution is passed across.

Rhubarb cells under microscope
Rhubarb cells

Rhubarb cells under microscope after they have plasmolysed
Rhubarb cells which have plasmolysed

Once they have seen this happen they can then try to explain what they have observed using the scientific ideas behind the process of osmosis.

Instructions for this activity are in additional links below.


In order for your students to be able to explain their observations what knowledge would your students need to have prior to this practical? When would you teach these concepts?

Post your ideas below.

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This article is from the free online course:

Teaching Practical Science: Biology

National STEM Learning Centre