U

unit

A single thing or group that is part of something larger.

unit of measure

A fixed quantity used to measure. For example, centimeter, foot, inch, and cubic centimeter are units of measurement.

unreasonable

Not making sense or "crazy."

using doubles

A strategy for adding and subtracting that uses a doubles fact you know. For example, use 7 + 7 = 14 to find that 7 + 8 is one more or 15.

using ten

A strategy for adding that uses a fact you know makes ten to solve another problem. For example, if you know 3 + 7 = 10, then 4 + 7 is one more or 11.