Following last weeks post featuring a box set on the price/prize minimal pair, here's a box set on the bean/bin distinction. Again, one person is the speaker and says one of the phrases. His/her partner is the listener and says which they understood - A, B, C or D. Success depends on the speaker creating the vowel sound distinction and the listener perceiving it - both parties are responsible for the outcome. The difficulty in this instance is that the English vowel sound distinction between bean and bin does not exist in many languages, which have a vowel sound about half way between the two instead. This vowel distinction is traditionally called long versus short in the British tradition, while in North America, tense and lax are often used instead. Long and short have the advantage of being simple and more transparent, but they're not entirely accurate. Firstly, the vowel difference between bean and bin is not only length - there is more muscle tension in the first and less in the second (as is suggested by the terms tense and lax). Secondly, vowel length is also influenced by context - we saw in last week's post how the vowel sound in peas is a little longer than in peace because of the consonant sound which comes after the vowel. Thirdly, long and short work better for some accents than others. For example, caught/cot are a long and short pair for General British (GB) but not for American.
Returning to our bean/bin pair, I personally still use the terms long and short in the classroom, while keeping in mind the above provisos. It's a pedagogical simplification. With long vowels, we often get our students to exaggerate the length and stretch it out. However, I usually find that it's the short one which is the problem. My student's default pronunciation of bin tends to sound like bean, so you get the long vowel whether you want it or not! For the short vowel, I work on exaggerating its shortness, using a hand gesture of abruptness such as a little karate chop movement. You can also try miming saying the words - that is, saying them silently. This helps students to notice the tenseness of the muscles (the smile) in the bean vowel, and the relaxed face of the bin vowel.
A final, more general point about pronunciation teaching: it has long been accepted that grammatical truth may be bent for teaching purposes - this is what we call a pedagogical grammar. It is sometimes justified to state a rule in a simple and memorable way to begin with, even if it is not entirely accurate. For pronunciation teaching , it's also the case that simplicity is often justifiable, even at the expense of accuracy. We could call this a pedagical phonology.
There are a collection of Box Sets in PronPack 3: Pronunciation Puzzles (forthcoming)