I am teaching Grade 11 Biology this year for the first time in seven or eight years, and quite enjoying it. One thing about doing a course you haven’t taught in a while is the joy of going back through your old notes and resources – it’s a bit like reading your old diary entries. There’s a bit of nostalgia for things you remember, and excitement at finding things you had forgotten.
In this age of computers, I sometimes forget how I used to explain things without having a zillion graphics and animations at my fingertips. One such explanation was for homologous chromosomes and the concept of alleles. I find that, despite the simplicity, many students have difficulty with the terminology and with conceptualizing genes and alleles. So the analogy I would use is clothing. I would have two students (ideally of similar height) represent a homolgous pair of chromosomes. Each “chromosome” has a gene for shoes, for socks, pants, and shirt. But the alleles may be different – one student might have the Doc Martin allele of the shoe gene, while the other has the All Stars allele. They might both have the blue jeans allele for the pants gene, and so on (of course, now I work at a school with student uniforms, so I have to compare my clothes to theirs to get different alleles).
It is a simple, low tech demonstration, but it seems to be quite effective at getting the point across.