Freezing and Melting Water Lab

Today I did a lab that tested the relationship between the freezing and melting temperatures of water. My lab group included Kira and Jake. The freezing temperature is the temperature at which a substance turns from a liquid to a solid. The melting temperature is the temperature at which a substance turns from a solid to a liquid. For this lab we used Logger Pro software to collect data. We froze and melted water in a test tube, and we measured the temperature with a temperature probe. We also used a ring stand to stabilize the test tube.
Here's a diagram I drew of the experiment:

My hypothesis for the experiment was that the melting temperature of water would be higher than the freezing temperature of water.

These were the results:


For the first test, we froze water in the test tube and measured the temperature. It's lowest point was about 
-4 degrees Celsius. 

The mean temperature of the frozen water (the freezing temperature) was about 0.6 degrees Celsius.

Also, here's a pic of the test tube with frozen water (with Kira in the background):

Here is a little video of the test tube (in the warm water beaker) as it melts:

Here is a graph showing the temperature of the water as it melted:

33.1 degrees Celsius was the highest temperature of the water. The melting point was at about 0.7 degrees Celsius, which is a higher temperature than the freezing point of water.

My hypothesis was supported because the freezing point of water was at a lower temperature than the melting point of water. 

In the beginning, the temperature dropped very drastically when the water began to freeze. It slowly stopped dropping and evened out after a while, then it rose. This was probably because the ice cubes were melting in the beaker. After that, we added more ice, and the temperature dropped again. 

The temperature of the water as we were melting it did not significantly increase in a small amount of time. However, over the period of 12 minutes, the temperature did rise. When my group and I lowered the test tube into the warm-water beaker, the temperature rose fast. Also, you could see a significant decrease of mass of the frozen water. It was clearly melting and dissolving into a liquid at around 13 minutes.

If I could do anything differently, I would have probably used Logger Pro graphs and diagrams to assess what was happening more clearly. Also, myself and my group were a little impatient, so we might not have waited long enough for each test, which could skew the temperatures at different times of the test.