We have the kids decide what two numbers that end in zero is the number between. Then we have them draw a hill and put the lower number on the left and the higher number on the right. Then we mark a line at the top of the hill and put the number in the middle there. Then we put the number we are rounding on the hill. I ask them if we were skating and had to suddenly stop on that number, which way would we roll. Then we teach them 4 or less, let it rest, 5 or above, give it a shove. Basically, its like the numberline, but we shape it like a hill. Hope this makes sense. I have been up for 2 days..