Yeast biologists will know this. You have a love-hate relationship with tetrad dissection. On one hand - it's the activity that requires 100% of your mental focus, and you can escape your busy day for a while. On the other hand, it's 9 PM on a Friday night and you have 6 full plates still to go.
Basically: yeast can exist with one or two copies of their genomes. When 2 haploid (1 genome copy) cells of opposite mating types meet, they form shmoos and can combine their nuclear contents to form a diploid cell (2 genome copies). When diploid yeasts are starved, they undergo gametogenesis or sporulation and form 4 spores, each with 1 haploid genome each.
Fortunately, the good chaps at the Carlsberg Laboratories whom I've mentioned before - Lindgren & Winde - developed techniques to analyse the recombination and segregation of genes in haploid & diploid cells.
In practice, this means I pick apart tiny yeast spores with a fine glass needle.
Imagine this: you have a plate full of gummy bears on a surface that has the same stickiness you might find on a sketchy nightclub floor. Most of the gummy bears are by themselves, but some are stuck together in clusters of 4. You are suspended upside-down from the ceiling, and can only manipulate the gummy bears with a meter-long stick. Your task is to pick up a cluster of 4, break it apart into individual bears, and place each individual bear on a pre-determined grid location. Now do that 19 more times for 1 plate, and complete the whole routine 5 more times because you've been putting this off for a while.
My record is 22m 15s for a full plate (20 tetrads). I'm looking forward to seeing how much quicker I'll be at the end of these 4 years!