Well, I first made all the solutions I needed, the EDTA and calcium chloride. I standardized the EDTA I made with a magnesium sulfate solution that I'd made, and I made my standard calcium chloride solution by dissolving calcium carbonate in hydrochloric acid.
I bought my first bottle of milk at the dairy, and I took it home and put it in the fridge. Then I carried it to school the day after, and put it in the school's fridge about an hour and a half afterwards (it's been so cold lately and the classes didn't have the heaters on, so I don't think this would have affected anything).
Throughout that week, I titrated the milk. Depending on how many titrations I had time to do (one, two, or three different temperatures), I would pour out the milk that I needed into a large beaker; the rest of the milk stayed in the fridge.
To heat the milk, I poured some milk into another beaker and put the beaker on a hotplate (which was far from my large beaker of milk). Once a thermometer showed that the milk had reached the temperature I wanted, I would take the beaker off the hotplate and placed it in a cold water bath.
Once the milk's temperature had decreased to 20 degrees Celsius, I would pipette the milk into conical flasks that already had the EDTA, KOH and indicator in them. I titrated four times for each temperature to firstly get a rough idea of the titre values, then the other tree titrations gave me concordant results.
I bought my second bottle of milk on Thursday, and kept it in my fridge until this morning, when I brought the bottle to school, where I kept most of it in the fridge and only took out enough milk for me to heat at three different temperatures. So I went back to the fridge to fill up my beaker twice after that.
I did the temperatures in this order both times: 20, 40, 60, 80, 100, 30, 50, 70, 90 degrees Celsius.