I went shopping for my supplies (A4 paper box - 'borrowed' from school, 4 mouse traps, masking tape and a knife/scissors) and found that they no longer sell those old school mouse traps with the wooden base and the metal springs! They now sell these fancy contraptions that you can stick your finger in and not risk it being chopped off. This made me happy as I knew I didn't have to worry too much about filling in an incident report on a Friday afternoon because a Year 12 student has lost a finger during my lesson! It only took me about half an hour to create, with the longest time being spent on cutting the holes at the front of the box.
So this is what the finished product looked like:
This drove a discussion on Tay Sachs. Not many of the students had heard of the disease, so I used the data projector to show them photos of children with the disease and read through some stories that I found online. This gave them a very brief introduction into the disease. I then posed the question, 'If you had a child with Tay Sachs (or any other debilitating disease that was passed on through genetics) would you have more children?'. Being Year 12 students, this led to some good conversation about genetic screening and the use of genetic counselling.
It was then time to pick our volunteer, who would be the first person to have a go at the 'Predictor'. We sent her outside and I opened the box and showed the rest of the class what was inside. I made them believe that the volunteer would be putting her finger inside one of the openings to see whether the trap would go off. It was explained that if the trap went off, their child would be born with the disease and if not their child would be healthy.
When our volunteer returned and was told what she was going to do, and everyone reacted accordingly! Of course I wasn't going to make her put her finger in the trap (safe traps or not - I'm not that sadistic!) so I handed her a paddle pop stick. She chose her box and we recorded whether or not the trap went off. Then we went through all students in the class and I re-set a trap for each student and we recorded our data. We achieved a result of 3 'yes' to 13 'no' and by doing our mathematics calculated that the percentage was approximately 23%. This was pretty spot on considering we had a small sample size and we achieved our 25%, which is in fact the chances of a healthy couple have a child with Tay Sachs.
This helped us end the lesson with an introductory discussion about recessive and dominant traits and how the percentage chance of many genetic traits being passed on from one generation to the next is dependent on these different types of genes and the chance is 'reset' with each generation.
I think once we get into actually looking at the inheritance of different traits this introductory lesson will help them out a bit and I'm sure I will get the 'Predictor' out again to explore the possibilities of passing on other traits!