I guess what every educator deals with is needing to find out what preconceptions there are at the start of the unit and then correct those and then keep on top of those throughout the course. For example I get students who use the word particle and the word droplet interchangeably.
I remember when I was taught this, that the only definition we were given was Le Chatelier’s actual definition, or his principle, and I remember reading that language and going geez, that’s really hard to follow as a student, so I used to always try and present that and then break it down in to a more simple sort of version that I thought would be easier to understand.
I was thinking about Le Chatelier’s principle and how that’s quite cumbersome in its wording, and so when I teach it, and how I always break that down into language that’s probably easier for students to understand, and Bob tells me that’s called repackaging, and I sort of thought that through all my teaching I do a fair bit of repackaging, a lot of the time, so I guess that was just a trait that I use and has been pretty successful for me, I think.
Start by defining the Q and K, and saying that Q is your tool. K is over here and it doesn’t change, but Q is your tool to assess how close we are to K in terms of the system.
Use red flags on lecture slides every time a 'new' defined word is used, to reiterate the meaning which is different to the meaning they might have encountered before. Even the word ‘equilibrium’ which has a meaning in the chemistry context and an everyday meaning. There will be literally a red flag on the slide.
Le Chatelier’s principle is quite cumbersome in its wording, so break that down into language that’s easier for students to understand - that’s called repackaging. Repackage of the concept and wording into language which students understand and can relate to. For example, if you heat the system up, both reactions get faster. One gets faster and faster and the other one gets faster and faster. That is good terminology that the students will understand.
Start with HA and move on to specific chemistry. Reinforce pKa and connect with buffers by asking students to pick conjugate acid/base combinations to make up buffers with different pH. Use the concept that adding strong acid to a buffer converts it to a weak acid, increasing the overall concentration of weak acid.
Ask the students to look at structures and consider what charge different parts of the molecules will have when they are protonated and deprotonated (eg. COOH to COO- is neutral to negative, and NH3+ to NH2 is positive to neutral, but can have OH groups that become O- sometimes, depending on the pKa). Use a table of amino acid structures and pKa values, and get them to work out charges at the pH of interest.
Explain partial charges, with problems, then link this to bond polarity. Explain the differences in arrows 'language'. Draw organic structures as line structures and no stereochemistry (until you discuss that). Make stoichiometry explicit and link the structures to names to build on the concepts.
Re-teach electronegativity quickly because you don't necessarily trust the person who's taught before you. Make sure that it's reiterated, and then follow through to bond polarity and partial charges. Include all of that information first before going on to do reaction mechanisms. So the first thing to do is draw in partial charges to identify the electrophile and the nucleophile before going on to the next step. It's about doing examples all the way from first principles to build up those concepts.
