You need to get them to build a "god's eye view" so that they can think, rather than just driving the dials - so I disagree with a few of FFF's points.
First point: avoid sums! There's no need to add/subtract RBI indications to/from headings. Get them simply to visually transpose the RBI needle on to the DI. This is easier than doing sums, as accurate as you want it to be, and is the same as using an RMI.
Next point: start by getting them to position fix (by reading the tail overlaid on the DI), then working out how to get to the beacon, then how to intercept tracks.
Next point: make sure they always know where the wind is, have an estimate of max drift and how the proportion of MD varies with relative angle.
Personally I don't like the push/pull approach, but lots do. I ask people what their track is and what track they want. If you're going "away" and want a bigger number you turn right (onto a planned heading, not randomly) - if you're going "towards" turn left for a bigger number.
Other points: Use the head when tracking "to" and the tail when tracking "from". Always leave the rotatable card "zero'ed". The head always falls and the tail always rises. Dip is easy to understand and the stude needs to know about it to understand what's happening - just teach it as the needle "falling" by half the bank angle.
HFD