Cheng Reaction – Practicals in Science
Michaela Community School, Wembley


Cheng Reaction – Practicals in Science

08 Nov 2017, Posted by admin in Michaela's Blog

Practicals in Science

Now that I’ve been at Michaela for over a year, I have come to see that one of the most enjoyable aspects of teaching science are our practical lessons. Whilst in the past this might have filled me with dread, the systems and logistics we have in place mean they run smoothly every time.


Before the practical

  • Knowledge – Firstly, we make sure pupils understand what the practical is about. For example, if year 8 pupils are completing a pondweed photosynthesis practical, we make sure pupils know the factors that limit photosynthesis. If year 9 pupils are completing a displacement reaction, we make sure they know the GCSE reactivity series off by heart. How we get the pupils to remember this knowledge can be found in a previous post here.
  • Practical skills lesson – before each practical lesson, we teach a practical skills lesson to discuss scientific skills, the equipment and terminology needed for pupils to make maximum gains during the practical lesson. This can be specific to the practical: for example, knowing the parts of microscope before looking at onion cells. On other occasions, we might look at broader aspects of practicals such as identifying hazards or risks, or possible variables. Pupils use self-quizzing to memorise these principles by heart.

Practical lesson

  • Expectations – In a practical lesson, the same high standards of behaviour are expected. Pupils are told that they must remain professional at all times. This includes everything from the use of lab coats and safety spectacles, to packing away equipment. Perhaps one element of practical lessons at Michaela that makes them markedly different from other schools that I have visited is the extremely low volume that our pupils maintain. At most, pupils may whisper when necessary in groups. We believe this is essential to ensure a calm and focused environment. We always model and practise ‘whisper voices’ before we begin, to clarify what this looks like.

Here are a couple of short videos of pupils completing practicals in class:

Miss Dyer : Heart Dissection 

Miss Cheng: Displacement reactions


  • Lesson outline – each practical lesson roughly has this outline.
    1. Recap (quick questions from the skills lesson);
    2. Reading instructions: equipment, risk assessment, method
    3. Practical
    4. Comprehension questions

After the pupils have done this a few times, these steps become fairly automatic.

  • Modelling – teachers always trial the practical before we teach it, taking pictures to model what the practical looks like. This leaves no ambiguity with things like setting up, and so on.


  • Visualiser – every Michaela teacher has one of these pieces of kit. It’s a great tool to have for all sorts of reasons, but in science, it can be brilliant for demonstrating practicals. For example, my year 10 class were recently dissecting hearts. I modelled this first on the visualiser so the pupils could identify all the parts and see exactly where to make incisions before they went ahead and did it themselves.


  • Routines– it is absolutely essential that strong routines are in place during practical lessons. This provides clarity and ensures safety at all times. For example, we assign different tasks to various pupils, such as sorting equipment into trays, or even carrying out different parts of a dissection. During the heart dissection practical, for example, pupil 1 made the first incision, pupil 2 made the second incision, and pupil 3 identified the blood vessels.


After practical

  • To make sure the practical was useful, and to consolidate the pupils’ learning, we give them a 25 mark exam paper on the practical. This ensures that the skills and knowledge they gained from the practical are linked closely to their theoretical understanding.

My HoD, Olivia Dyer has previously written about the principles behind practicals at Michaela here.

If you would like to visit Michaela and see us in action, email

Sorry, the comment form is closed at this time.