You shouldn’t be rigid in what you’re going to do. Go with the flow in the lecture. Don’t be rigid and think ‘I’ve got to get through these 15 slides today and if I don’t the world will end’ because it won’t.
Write your course before the semester starts so that you know what the flow is and what the connections are. If you’re always writing one lecture ahead of them you have no idea what’s coming in the future therefore you can’t make the connections across the whole set of lectures. It’s very important to be able to know what’s coming, know what’s gone behind and know what you’re doing at the moment.
Use a lot of eye contact, the people in the back row are not anonymous, make sure you’re talking to them and make sure that you see them. Make sure you’re looking at them. So you’ve got to focus on the whole class not just the people at the front, the people at the back as well.
So the strategy is to reflect, to change things, to be flexible, to talk to them but not talk down to them, and don’t be writing the lecture the night before.
Use physical and tactile experiences to demonstrate intermolecular forces. For example, If you stretch a plastic grocery bag (made of polyethylene), the length increases and the width decreases. This breaks apart the London Dispersion Forces (induced dipole-induced dipole interactions) and straightens out the polyethylene chains. The covalent bonds remain intact until the plastic rips.
You can get the students to physically feel that liquids are not compressible by giving them three closed syringes: one contains water, say 50 mL, that’s been put in the freezer to become ice; another syringe contains 50 mL of liquid water, and the other one is gas. Ask them to push the syringes and see what happens. They find they cannot push the syringes containing liquid or solid, even though they think there would be some space in the liquid one. The misconception is that liquids fall somewhere between solid and gas and so should be “a bit” compressible.
Keep going back to applications in the real world. How is it that geckos can crawl up a wall, and sit on the ceiling without falling off? How is it they’re able to stay there with gluey legs or something? How do they maximise the attractions between the molecules in their feet and the molecules in the ceiling? Show applications that are powerful, and hopefully interesting, of the ideas that are important.
Use the Vis Chem website, which is Roy Tasker’s resource, and there are links to a Scootle site where you can download visualisations for chemical bonding and pure substances in different states. There is gaseous water and liquid water. You can see they’re close together - they’re crowded. You can talk about ice skating. You can press the ice and it becomes liquid. That’s why the ice skates slide. You can see they’re jiggling away. There’s some space between them.
Students tend to think that large-scale analogies are appropriate. For example, billiard balls colliding. Use such analogies but then deconstruct them for an introduction to quantum mechanics.
