I really don't like broken strings. It takes class time to fix strings and they are expensive. So, I give a lecture about tuning and post some rules about tuning to help students remember what to do in order to NOT break a string.
This poster is available as a download HERE:
First, I show students a rubber band (ideally I would pass out a rubber band to each student) and I stretch the rubber band super tight. Students can experiment with the rubber bands to discover that the tighter they stretch the bands, the higher the pitch will go.
We then look at our instruments so students can discover which way they must turn pegs or fine tuners to make the string tighter or more loose.
I then begin an ear training exercise. I should really do this every day for the entire first week, but sometimes I forget. I tune my violin to a tuner that plays each pitch. I ask students to compare my violin string with the tuner note and they show me a thumbs up if my string is too high and a thumbs down if my string is too low. It was very interesting for me to see that many students have difficultly hearing the very small differences in pitch. There is a game at www.fiddlerman.com that helps students practice hearing tiny adjustments in tuning and intonation. I have had students play this in the computer lab with headphones: http://fiddlerman.com/fiddle-learning-tools/intonation-game/
The last step is to have student try it! The only way they will learn is to have the experience tuning themselves. I play 4 open A's and students then echo back on their A strings. I ask them to determine if they are too high or too low. Then they must make the adjustment while plucking or playing. This took a long time on the first day, but now we get it done in just a few minutes and we have had no broken strings.