When faced with complex, tricky topics to teach, such as electrolysis and moles, we teachers chunk down the information, modelling and questioning to help students’ understanding. But what about the areas of knowledge they have no connection with, and so are harder to learn and understand, but they need to know simply for the sake of knowing? How can we make those relevant?
Let’s take coarse, fine and nanoparticles as an example. Nanoscience is a relatively new and interesting area, however, the comparison to fine and coarse particles and their relative sizes is not. A good starting point could be to model the sizes of the different-sized particles, anything from an electron to a grain of sand.
Set up three trays, each with one of the following labels: coarse, fine or nano. Ask the class to imagine they are using a powerful microscope to see the particles. In the course tray use small pebbles/building sand and show a handful to the class. In the second tray use a finely powdered material, such as icing sugar, and point out the difference in size. ‘Here are the fine particles. How much bigger are the pebbles?’ Now point out: ‘If we go the other way, fine particles are 100 times smaller than coarse. Nano are 100 times smaller than the fine particles … and here they are.’ Then, dramatically move onto the seemingly empty tray as you cannot see nano with the naked eye.
Be particular about particles
Why is there a difference between coarse, fine and nano? A simple, effective demonstration is to drop the pebbles and sugar into water and tell students to note their observations. Coarse sinks but fine floats. Ask how they imagine nanoparticles would interact. Of course, they can interact in highly unpredictable ways, such as causing colour changes (e.g. you could show images of gold nanoparticles in water). Other chemical reactions can occur due to the high surface area to volume ratio, as in this Burning milk powder demonstration.
Many students believe cells to be some of the smallest things possible
Help students learn the differences by pinning these ideas to other particles they have studied. This can be challenging as they cannot see them. Using animations can be powerful and works well as an introduction to atoms and subatomic particles. This animation, allowing investigation into the science of both small and large objects, helps make the concepts more concrete. It often generates a good number of questions around the different objects and, in particular, is able to highlight the difference in size between biological cells and atoms. Many students believe cells to be some of the smallest things possible, due to their experience with microscopes.
Another useful animation that never fails to impress is one I use for introducing the concept of subatomic particle size. But it’s also helpful when comparing particle sizes more generally.
Why is there a difference between coarse, fine and nano? A simple, effective demonstration is to drop the pebbles and sugar into water and tell students to note their observations. Coarse sinks but fine floats. Ask how they imagine nanoparticles would interact. Of course, they can interact in highly unpredictable ways, such as causing colour changes (e.g. you could show images of gold nanoparticles in water). Other chemical reactions can occur due to the high surface area to volume ratio, as in this Burning milk powder demonstration (rsc.li/3HknQ7O).
Many students believe cells to be some of the smallest things possible
Help students learn the differences by pinning these ideas to other particles they have studied. This can be challenging as they cannot see them. Using animations can be powerful and works well as an introduction to atoms and subatomic particles. This animation, allowing investigation into the science of both small and large objects, helps make the concepts more concrete (bit.ly/3ZqeQnW). It often generates a good number of questions around the different objects and, in particular, is able to highlight the difference in size between biological cells and atoms. Many students believe cells to be some of the smallest things possible, due to their experience with microscopes.
Another useful animation that never fails to impress is one I use for introducing the concept of subatomic particle size (bit.ly/4k4dfMP). But it’s also helpful when comparing particle sizes more generally.
This kind of activity helps consolidate students’ ideas and you can help them unpick any misconceptions they may have and so can work for other topics, such as atomic structure. They need to grasp the concept of size. For example, which is bigger – atom or positive ion? The nucleus of an atom or the nucleus of a cell (a common misconception)? A molecule of oxygen or an atom of oxygen? A fine particle or an atom? You can quickly review answers using mini whiteboards. The next phase is to ask students to sequence the particles in order of size. For example, a nanoparticle, an atom, a proton, a coarse particle, a helium nucleus and a carbon dioxide molecule.
More resources
- Read The many uses of nanomaterials to introduce learners to the most up-to-date applications of nanoscience. Download the accompanying structure strip to help learners with extended response questions.
- Make your own sunscreen and determine its SPF using UV light transmission with this resource package, suitable for a sequence of timetabled lessons, science clubs or during an activity day.
- Share how scientists use silver nanoparticles in medicine and career profiles of those working with nanomaterials, such as nanotoxicologist Vicki.
- Explore the scale and size of atoms and their relation to elements, introducing students to nanoscience with this lesson plan with activities for 14–16 learners.
- Provide context to nanoparticles with stories and summary slides on blueberries and colourful smoke.
I have enjoyed using these resources and techniques in lessons to bring so-called dry topics to life and help students both contextualise and deepen their understanding. I hope you find them useful too.
