This is the first "real" lab. I generally start the class explaining what annealing is and why we're doing it, point out where the materials are, and then sit down. My approach is deliberately hands-off.
Each semester, I am amazed that this protocol takes students an entire two-hour lab period. It probably has to do with my hands-off approach, as mentioned above.
Students often struggle with the dilution math. Remind them of c1 * v1 = c2 * v2 and remind them that they've already done this once. Suggest that they review the dilutions and pipetting lab and that they ask their colleagues for help. Only if students are really stuck will I review the procedure with them.
We've only got one thermocycler -- but this reaction is fine to wait until the entire class has loaded their samples to start. (As opposed to the PCR, which needs to stay on ice until it's time to start.) So I ask students to load their samples into the thermocycler as they finish.
As students load their samples, double-check that they look like about 10 µl of liquid. Significantly more may be a sign of a pipetting error.
As students load their samples, double-check that they're labeled. Remind them that their tube will be one of many and ask if they'll be able to pick their tube out from all the others?
Remind students to record their tube label in their notebook.