Use Roy Tasker’s video model VisChem, or Kahn Academy, and post on Blackboard. There are a lot of online formative practise quiz questions, for example, in Kahn Academy.
Use Lego pieces. For example, HCl built out of Lego. Use a little blue brick and a yellow one, showing physically that on this side you’ve got one blue Lego brick and then on this side you’ve got two and so on, trying to make them see them not as chemical formulas but identities of some sort.
In the lab you can get students to weigh out quantities and react them and then do calculations for the yield, so they’re applying it. That’s the way in which they come to terms with what they’re actually doing and the molar basis for that. It’s about representing what’s going on, on a molecular basis. We handle things on a molar basis because they’re the amounts we can weigh, and it’s representative of what’s going on on the molecular scale. It’s just scaled up by 6 x 1023.
Try demonstrating the reaction first, to show the macroscopic changes that occur, before introducing the equation. Copper in silver nitrate solution is a standard one. Explain it in terms of particles, the ions, atoms, show a video representation (for example from YouTube) of these changes, and then explain the whole thing in terms of the symbolic chemical equation to represent the overall change.
You can use analogies to everyday objects and there are a variety of things you can use in that way, such as pebbles and peas to illustrate moles, because they have different masses. Certainly getting them to think about that and then to be comfortable in translating that into a whole lot of different elements you might be comparing.
Use the example of something obvious, such as reaction between two compounds, and you get 200 tons of one, and half a gram of the other one - which one is the limiting reagent, and why is it the limiting reagent? Because you run out of it before you run out of the other one. It’s something that they can imagine, something they can see. Or even in the lab, if you don't have 200 tons but one litre of one and a few milligrams of the other.
