Rounding to nearest Hundred

To help my child learn the concept of rounding to the nearest hundred I used two sentence paper strips to make a number line from 100-900. I cut out 2 x 2" squares of card stock and wrote on some random numbers. We made a little game out of finding which 2 hundreds the given numbers were in between, laying the given number on the number line. Then I marked off the "middles"...150, 250, 350 in red...explaining that if the tens place of the given number is 5 or above then you round up to the next hundred. For example 252 would be rounded up to 300 since the tens place is a 5 or above. I presented this to my daughter by placing the numbers under the correct answer.