The way back-titrations are taught is often confusing. Get them to concept map the calculation. So, instead of trying to do the calculation in their head, map it out starting from where they end up, and then relate each of those steps to where that number is coming from. Have them think about it like it’s a reaction. Because they know how to do the math, and they can understand how to do it for a reaction. An example is the dissolution of calcium carbonate and trying to get them to work out how much carbonate is in a limestone sample.
Try and get across the bigger picture - everything you're going to do is going to be a model. Nothing is going to be right. Nothing is going to be wrong. Nothing is going to be exactly the way it is. Everything is a series of models.
Try to show students that the fundamental form of matter is energy. Then that this can be represented as particles with mass or as waves (wave functions). Link to YouTube Video: Particles and Waves
Students come in, like all of us, trying to apply macroscopic analogies to everything – (the billiard balls colliding and similar things) and using them as models for atoms. Try to get across that it's a simple analogy but it's not as simple as that in reality. I guess go back a step and try and show that everything is really just a form of energy.
Use molecular models, simulations, Lewis diagrams, ball and stick models, space filling models. Different representations - macroscopic and microscopic. Make sure you know how to use them.
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.
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.
