I've had two weeks with these 12 students, about half of whom I had for QM [remedial math] 2 years ago. As in recent years, I'm going to appoint each pair in rotation to the rank of Autoclave Liaison Officer ALO. At least some of our students will be confident and comfortable with this potentially
1) the number of each type of Petri dish
2) the weight of just the plastic - count x 13.15g
3) the total weight of all the plates less the plastic
4) the average weight of each filled plate
5) the standard deviation of each batch
I've highlighted the lowest Standard Deviation [in the 3rd data column] because those boys were clearly in the zone when they were pouring - each plate the same as the last. But they still have things to learn. Expecting to pour 20 plates, they had labelled 20 empties before pouring because they poured a little mean, they only used 401g of their half litre of agar. That's enough to make 4 or 5 extra plates from the batch. But the lazy arses decided not to label the extra plates; preferring to throw away the surplus agar. If we have enough starch agar plates for the class next week, that was a good call. If not then someone will have to go sort in their investigations at the frontier of science. In the interests of nerdnik completeness here is the analysis of variance which shows clearly that there is a significant difference in the average weight of Petri dishes poured last Thursday - tsk on the quality control, lads.