Grade:4
*This is a lesson I taught on rounding. I noticed that the students were struggling with using a number line, so I developed this so that students can actually visualize the gravity pulling the roller coaster towards a rounded number.
1. Put the roller coaster ramp on the overhead. Look at your number that needs rounded and decide what you are rounding by (tens, hundreds, etc).
2. At the start of the roller coaster, write the number that you would round down to. Then at the end of the roller coaster, write the number that you would round up to. For example, if the number is 129, and it’s instructed to round to the nearest hundred, one would write 100 at the start, and 200 at the end.
3. Now write the middle number at the peak of the roller coaster ramp.
4. Now find where your number that your rounding is located on the roller coaster ramp – just as if it were a number line.
5. Put your roller coaster rider at that spot on the roller coaster ramp. Now the students can easily look at the roller coaster and easily visualize which way the roller coaster will fall, hence knowing which number to round to.
6. This roller coaster rounding concept can be adapted for all sort of numbers and rounding situations.
