1 - set up 4 boiling tubes, one with dry cotton wool, one with moist cotton wool, one with boiled and cooled water with a layer of oil on the top and another with moist cotton wool
2 - place ten cress seeds in each boiling tube
3 - place A, B, and C in an incubator, and place D in a fridge
4 - leave for a week to allow the seeds to germinate
5 - count the number of seeds in each tube that have germinated.
CONTROL VAIRABLES - species of seeds