standard_description: Understand that the two digits of a two-digit number represent amounts of tens and ones. Understand the following as special cases:
- The numbers from 11 to 19 are composed of a ten and one, two, three, four, five, six, seven, eight, or nine ones.
- The numbers 10, 20, 30, 40, 50, 60, 70, 80, 90 refer to one, two, three, four, five, six, seven, eight, or nine tens (and 0 ones).
- 10 can be thought of as a bundle of ten ones — called a “ten.”
problem_activity: Identify whether the following statements are true or false.
a.   A parallelogram is always a trapezoid. T / F
b.   A quadrilateral is always a parallelogram. T / F
c.   A parallelogram is always a polygon. T / F


aligns: no