Particles is a year 4 thing…

When drawing up my map of the primary science curriculum last year, I was struck by some of the links between units I hadn’t realised before. In particular, I had never realised why it made sense to teach States of Matter and Sound close together, given that the children can explore how sounds travel in different materials. One of Harlen’s (2010) big ideas (in fact the very first big idea) is “All material in the Universe is made of very small particles.”

With this in mind, it got me thinking about how we approach the idea of the structure of materials, and in particular, the fact that they are made from smaller particles. This also links into how we think about sound and vibrations later in year 4, and also to some extent when thinking about electricity too.

It’s important to remember that the particle model is a KS3/4 concept and does not form part of the KS2 national curriculum. It is often felt to be a difficult concept for younger children. This also explains why there’s no mention of Energy in the English Primary Curriculum. However, research has shown that teaching some aspects of particle theory in KS2 does make some sense (Allen, 2016), particularly in using the idea of the arrangement of particles to explain the general nature of solids, liquids and gases (Skamp, 2005, Lee and Tan, 2004). Leisten (1995) found that primary children are able to use terms such as “atoms” and “molecules” in everyday language and can understand the concept that materials are made of much smaller subunits.  

In addition, Donovan & Haeusler (2016) found that Year 4 is an opportune time to introduce children to particles (although as part of a spiralling curriculum that introduces concepts slowly over a few years). Lee and Tan (2004) found that there are benefits to using the particle model to enhance conceptual understanding of everyday phenomena such as melting and evaporating.

So where do we start? We can think of all substances being made of “stuff” (Skamp, 2005) and all stuff being made of tiny particles which (at this level) we can think of as tiny balls that are too small to see, even with a microscope.

“Stuff” is a good place to start. If I blow up a balloon, the balloon is now heavier (a concept that still confuses the adult student teachers I work with). Why is it heavier? Because there is now more stuff inside the balloon. And that stuff has to weigh something.  

So, if everything is made of tiny particles, we can then think about how these particles are arranged. And the way these particles are arranged can explain how the material behaves.

First, ask the children to explore the macroscopic properties of solids, liquids and gases – to look at how different objects feel and behave. This can be linked to the particles that make up the object.

A solid is made of tightly bound particles which are close together. A solid is rigid and has a definite volume and shape. Think about a cup, it will still be cup-shaped wherever you put it. Because the particles are so close together, a solid cannot be compressed.

A liquid is a material made of particles that are very close together, but not as tightly joined together as they are in a solid so they have more freedom to move. This means a liquid has a definite volume but no fixed shape.  It can flow and take the shape of its container, but because the particles are close together a liquid cannot be compressed.

In gases, the particles are not joined together at all and so are free to move and spread out. A gas has no fixed shape or volume and will expand to fill the entire space available to it.

For a good visual demonstration of states of matter, take a look at this simulation from Phet.

Making children aware that the properties of an object or material may be related to the stuff of which it’s made may be a quite a step up in understanding. Evidence suggests primary teachers should place emphasis on the macroscopic properties of matter first (Skamp, 2005) and the teacher needs to decide whether going into the detail about particles is appropriate, in terms of content, context and the ability of the children (Lee and Tan 2005).

To move the concept forward, other objects can then be introduced that maybe don’t behave exactly as you might think. Varelas et al. (2008) describe using different material artefacts in a class sorting activity to promote scientific discussion. “Ambiguous” objects, such as a plastic bag full of air, shaving cream, a bag of salt etc encouraged the children to debate ideas about states of matter.

For some great teaching resources on Matter (and other aspects of Chemistry) visit the Royal Society of Chemistry “Steps into Science” site.

Misconceptions

Use diagnostic questions to see what misconceptions the pupils have. Show them a deflated balloon then blow it up. Ask the pupils what they think will have happened to the mass of the balloon. Has the mass gone up, or down? Ask them to explain their reasoning. Some pupils will think that since gases are light, and that they float, the balloon will have become lighter.

Explain to the pupils that air is made of “stuff”, or matter, made from particles. Air must have a mass, just like all materials. They probably would all agree that a balloon filled with water would have got heavier. Air also makes the balloon heavier, but by a very small amount. If we had some very accurate scales we could measure this difference and prove it.

Common misconceptions the pupils have include the idea that since gases can’t be seen, there is nothing there and they have no mass. Or that water freezing or melting causes a change in mass.  You can actively assess understanding in these areas, for instance by asking pupils to draw and annotate pictures and diagrams to demonstrate their understanding as they progress through the topic.

Evaporation and Condensation

The Year 4 States of Matter unit also asks children to think about the water cycle and the role of evaporation and condensation, and this too can be explained using knowledge of particles. The conservation of mass when changing from liquid to gas can typically be a difficult concept to explain (SPACE Report, 1991)

Tytler et al (2006) used a sequence of activities to model changes of state and relate these to particle diagrams. Pupils observed different activities and were encouraged to use the idea of particles in the diagrams they drew to explain what was happening. These included a cold can, to explain why condensation appears on the outside. A disappearing wet handprint and why the smell of eucalyptus oil spread through the class.

The children were allowed to observe phenomena for themselves, and then asked to explain what they observed by drawing particle diagrams. The visual nature of the representation of particles in the air was particularly helpful for students to imagine the way perfume or water could exist in the air and be distributed around the room.

Bringing in the idea of the water cycle allows for all these changes of state to be described and discussed in the context of water.

Moving on from year 4, the idea of particles can come in again in year 5 when thinking about dissolving and other physical and chemical changes.

Linking Particles to Sound

Once the students have been exposed to the idea that solids, liquids and gases are made of tiny particles then this idea can be revisited when teaching about sound (if this is timetabled for later in the year).

When we think about how sound is travelling, we talk about vibrations. But what is it that’s vibrating? It’s the particles that pass this vibration through the medium. Why does sound travel faster through a solid or a liquid than a gas? It’s because the particles are closer together.

Particles and Electricity

Electricity is a difficult thing to explain in year 4, and although we don’t need to go into a lot of detail, there is still a need to try and form some kind of model for what is happening in a circuit. The concept of an electron is not officially introduced until KS4, although it often comes in at KS3.

As explained by Chapman (2014) we can again go back to the idea of particles to help with a model. We can talk of small particles in the wires that are able to move and carry something called charge, and this charge causes the electrical effects we can see.

For some models to help understand electricity, take a look at this from the IOP

Summary

So as you can see, there are some interesting links to be made between several of the units in year 4. It might be best to structure the year so that States of Matter comes before Sound and Electricity. What are your thoughts on this? Do you introduce the idea of particles to year 4 or do you think it’s too early?

Let me know what you think in the comments below.

References

Allen, M., (2016). The Best Ways to Teach Primary Science. Open University Press. Chapter5 Properties of Everyday Materials

Chapman, S. (2014) Teaching the Big ideas of Electricity at Primary Level. Primary Science 135

Department for Education. (2013) National Curriculum for Science https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/425618/PRIMARY_national_curriculum_-_Science.pdf

Donovan, J., & Haeusler, C. (2015) Developing scientific literacy: introducing primary aged children to Atomic-molecular Theory https://core.ac.uk/download/pdf/211496769.pdf

Harlen, W. (ed). (2010) Principles and Big Ideas of Science Education. ASE. Available from: https://www.ase.org.uk/bigideas

Lee, K-W. and Tan, S-N. (2004). Atoms and Molecules: do they have a place in primary science? Primary Science Review, 82, 21–23.

Leisten, J. (1995) Teach atoms earlier! School Science Review, 77(279), 23–27.

Skamp, K. (2005) Teaching About Stuff. Primary Science Review 89

SPACE research report (1990) Evaporation and Condensation https://www.stem.org.uk/resources/elibrary/resource/29217/space-project-research-report-evaporation-and-condensation

Tytler, R., Peterson, S. & Prain, V. (2006). Picturing evaporation: Learning science literacy through a particle representation. Teaching Science. 52. 12-17. https://blogs.deakin.edu.au/asell-for-schools-vic/wp-content/uploads/sites/160/2018/03/Tytler-et-al-Teach_Sci_evap.pdf

Varelas, M., Pappas, J., Kane, J., and Arsenault, M., Hankes, J. and Cowan, B.M. (2008) Urban Primary-Grade Children Think and Talk Science: Curricular and Instructional Practices That Nurture Participation and Argumentation. Science Education 92.1 pp65-95 https://onlinelibrary.wiley.com/doi/10.1002/sce.20232

Image sources

Title image from Pixabay: https://pixabay.com/photos/a-glass-of-water-color-ink-blood-210632/

States of Matter image from Wikimedia: https://commons.wikimedia.org/wiki/File:States_of_matter_En.svg