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.
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.
