How can I help students to round numbers?
A number line is a versatile visual model for showing
the position of one number relative to another
For example, what's the position of two-hundred
relative to one-hundred?
Two-hundred is double the distance from zero
to one-hundred.
That's right.
Now let's jump farther along the number line
and let's give it a different look.
Now imagine I placed a ball on the line to
show the position of five-hundred forty.
How would the ball help me know which hundred
is closer?
It would roll back to five-hundred.
That's right.
Let's say the ball was positioned at five-hundred
seventy.
How would it help me know which hundred is
closer now?
It would roll forward to six-hundred.
Yes.
So giving students visual experiences of locating
numbers
on curved number lines can make the idea of
rounding easier to understand.
