Compare temperatures involving negative numbers

What temperature is 8 degrees more than minus 5 degrees? Well, we have our number line thermometer here, so if we start at minus 5 and []count on 8, we get to 3 degrees, so if it’s minus 5 degrees and the temperature goes up by 8 degrees, []we get 3 degrees. But rather than using a number line to count through zero, let’s try a quicker method: []if we start on minus 5 degrees, we know that adding 5 degrees will take us to 0 degrees. Then, []from 0 degrees, we can add 3 degrees to get 3 degrees. []So, because we added 5 and then added 3, we added 8 altogether: so, if you need to add something to a negative number, you can add as much as you need to make 0, then add the rest.[][]
Now, what temperature is 7 degrees less than 3 degrees? Well, we have our number line, []and when we count back, we get minus 4, []so if the temperature starts at 3 degrees and then gets 7 degrees colder, the new temperature is []minus 4 degrees. But again, let’s use a quicker method, rather than relying on our number line: []if we start at 3, we can subtract 3 to get 0. Then, []from 0, we can subtract 4 to get minus 4. []So, because we subtracted 3 and then subtracted 4, we subtracted 7 altogether: so if you need to subtract to make a negative number, you can subtract as much as you need to make 0, then subtract the rest.[]