Quadrilateral

A square has these features:

1. 4 right angles that are 90 degree angles that make the 4 corners
2. all sides equal in length
3. closed shape
4. 2 parallel sides

A parallelogram has these features:

1. two set of parallel lines
2. opposite sides are equal in length
3. closed shape
4. opposite angles that are equal–obtuse or acute or right angles

A trapazoid has these features:

1. one set of parallel lines
2. sometimes the sides have the same length
3. most of the time they have different lengths
4. corners are different