"Place points on a number line. Round these values to the nearest ten or hundred.
Visualize rounding by showing the number line as a hill or series of hills.
These hills cause the points to roll to the nearest valley (nearest multiple of
ten or one hundred)."
"Launch clowns from a circus cannon and try to hit the target. Drag digit cards
on the control panel to set the launch distance and choose an appropriate unit
of distance. After practicing your clown-launching skills on a number line, move
on to the Big Top, Football Field, School Buses, the Golden Gate Bridge, and
more!"