Speed

Dividing distance by time to express speed is organized into three uses: Finding the Speed, Finding the Distance and Finding the Time. Two-step problems follow, along with unit conversions linking speed per hour, per minute and per second, and comparisons between speeds given in different units.

Treating 1 hour 20 minutes as 1.2 hours is the most frequent error. Any answer that used the time as a decimal without converting to minutes is this pattern. In unit conversion, children multiply by 60 where they should divide, and the ordering of speed per second and speed per minute comes out backward.

Amount per Unit Quantity compared quantities that stayed still; here the same idea is fitted to people and objects in motion, and organized into three ways of finding speed, distance or time. These three ways are applied in grade 6, when Traveler Problems combines the motion of two people at once.