We started subtracting integers today.
We used our trusted friend the racoon (now called Rabies the Racoon by some) to help us understand that adding a negative integer is the same as subtracting a positive integer. This makes perfect sense if we think of this in terms of balloons and weights. Adding a weight has the same effect as subtracting a balloon. The basket goes down. This means that we can convert any subtraction problem into an addition problem - just reverse the signs!
Here is a YouTube video that might help.