2. G EOMETRY V OCABULARY A Third Grade Unit

3. CENTIMETER A metric unit used to measure length. 1 centimeter

4. L INE S EGMENT A part of a line. A line segment has two endpoints. It starts and stops.

5. L INE A straight path that goes on forever in both directions

6. H ORIZONTAL A line that extends from left to right.

7. VERTICAL A line that extends up and down.

8. P ARALLEL LINES Lines that never intersect or cross.

9. P ERPENDICULAR LINES Two lines that cross or meet to form right angles or square corners.

10. PERIMETER The distance around the outside of a figure. To find perimeter all of the sides in the shape are added together. side + side + side = perimeter 4 cm 3 cm 4 cm + 4 cm + 3 cm = 11 cm

11. QUADRILATERAL A figure with four sides.

12. A DJACENT SIDES Two sides that meet at a point. They are next to each other. They are NOT opposite each other. a b c d Sides a and d are adjacent to each other. Sides a and c are opposite each other.

13. PARALLELOGRAM A quadrilateral with both pairs of opposite sides parallel. Only one set of opposite lines are parallel.

14. R ECTANGLE A parallelogram that has 4 right angles. Opposite sides are the same length. 4 cm 2 cm

15. SQUARE A special rectangle with four sides of the same length and four right angles. 3 cm

16. RHOMBUS A parallelogram with equal sides. A rhombus does not have to have right angles but it can. 3 cm 2 cm 4 cm