### Video Transcript

What is the difference between the temperature at which water boils and the temperature at which water freezes?

This problem is all about facts to do with temperature, and if we don’t know those facts, we’re going to find it difficult to actually answer the question. The two facts that we need to know are the temperature at which water boils and the temperature at which water freezes. And if we know those two facts, then we’re able to calculate the difference between these two temperatures.

Let’s remind ourselves of these two facts about water. We can measure temperature in degrees C, which stands for degrees Celsius. The first fact that we need to use in this problem is about how water boils. Water boils at 100 degrees Celsius. On this particular thermometer, that’s here. When the temperature of water gets to 100 degrees Celsius, it starts to boil.

The second fact that we need to know is the temperature at which water freezes. This one’s fairly easy to remember. If we’ve got a fridge or freezer at home, we can see this temperature written on it. Water freezes at zero degrees Celsius. So, if we bring down the temperature until it gets to zero, it will start to turn to ice. Water freezes at zero degrees Celsius.

We can think of a thermometer as just being like a vertical number line. On this particular number line that we’re looking at, each of the marks is worth 10 degrees Celsius. So, the question asks us, what’s the difference between the temperature at which water boils and the temperature at which water freezes? In other words, what’s the difference between 100 and zero?

The difference between 100 and zero is 100. And so, the difference between the temperature at which water boils and the temperature at which water freezes is 100 degrees Celsius.