Teacher's notes

There is enough material in the kit for 20 students and you could use it once with a class of more than 10, or twice with classes of 10 or fewer.
There are two positive serum samples marked with a red sticker. You should use one of these each time you use the kit (so if you have a class of more than 10 students you will only need one of the positive samples).

Preparation

The only preparation required is to dilute the wash buffer 1:20. There is 25cm3 of wash buffer containing detergent supplied. For 20 students use all the buffer and make it up to 500cm3 with distilled water. For smaller classes split the buffer and make it up accordingly. Each pair of students should be given about 50cm3 of wash buffer in a labelled beaker. To dispense it they also need a clean pipette (not supplied).

Each student should be given;

  1. a sample tube containing their ‘serum’ sample (one student must have a positive sample – remove the red dot so they don’t know who has this).
  2. a small pipette for exchanging ‘serum’ samples.

Each pair of students should be given (items 8-11 not supplied):

  1. a strip of 8 plastic wells
  2. a pipette containing enzyme substrate (blue B)
  3. a pipette containing the positive control (red +)
  4. a pipette containing the negative control (green -)
  5. a pipette containing the ‘primary antibody’ (yellow PA)
  6. a pipette containing the ‘secondary antibody’ (white SA)
  7. a beaker containing about 50cm3 of wash buffer containing detergent
  8. a pipette for use with the washing buffer
  9. paper towels
  10. scissors to cut the tips off the sealed pipettes
  11. marker pen

Spreading the infection

You will need to work out how many rounds of exchanges you get the pupils to do. Ideally aim to get about half the students infected. After the first round of exchanges two students will be positive, after two rounds four, after three a maximum of eight and after four a maximum of sixteen. It is important that the students keep a record of who they have exchanged with and the order of the exchanges. The first exchange will be with their partner. For the second exchange they should not both exchange with the members of the same pair.

Doing the test

Students should follow the instructions on the printed sheets. The test is fairly forgiving so there are a number of possible mistakes that will not affect the outcome. If you are short of time you can reduce the first incubation stage from five to two minutes, and the two antibodies do not really need any incubation time (two minutes each in the instructions).

Questions

Amongst other questions students could be asked to explain the purpose of the positive and negative controls and the reason for testing each sample in two, identical wells.