Overview from Everyday Mathematics
"In this Unit, children work with linear measures and review and extend their use of thermometers and clocks. They measure in nonstandard units, such as digits and hand spans, as well as in the U.S. customary units of inches and feet. They use rulers and tape measures to practice measuring classroom objects and themselves. Children also begin the important work of achieving "automaticity" (automatic recall) of basic addition facts."
Unit 4 has three main areas of focus: