Measuring the SHC of water

 I inserted a 12V heater through polystyrene into a beaker of water. I pushed a thermometer through as well.

I put bubble wrap round.

You'll be able to tell from the photo that I had first found the mass of the water. 

I took the temperature every minute for 12 minutes and plotted a graph of temperature against time. At first, the temperature stays constant and then goes up steadily. I drew a straight line through the section of steady heating. The water must be stirred whilst being heated. The equation is Delta E = m.c.Delta(theta). Delta E, the energy added = current x voltage x time in seconds. Delta(theta) is the temperature rise. Putting the two equations together, we get Delta(theta)/time = current x voltage /mc. But Delta(theta)/time = gradient of straight bit of the graph. So in the end, specific heat capacity              c = (current x voltage) / (mass x gradient).