##### Geometry

4th grade, 5th grade

Square

all sides are the same length; there are four right angles

rectangle

opposite sides are parallel and the same length; there are four right angles

parallelogram

two pairs of opposite parallel sides

rhombus

two pairs of parallel sides; all sides are the same length

trapezoid

only one pair of parallel sides

equilateral triangle

3 sided polygon where all sides and angles are the same

isosceles triangle

3 sided polygon where 2 sides and angles are the same

scalene triangle

3 sided polygon where no sides or angles are the same

pentagon

a five sided polygon

hexagon

a six sided polygon

octagon

an eight sided polygon

regular polygon

a polygon where all sides and angles are the same.

point

a location in 2-D space where you often make a dot with a pencil to show where it is and you use a capital letter to name it

line segment

it is made up of 2 points and the straight path between the 2 points and you use capital letters to name it

line

it is the shortest distance between 2 points that has no beginning and no end; you use capital letters to name it

ray

it is a straight path that has a starting point and goes on forever in the other direction; you use capital letters to name it

parallel lines

two lines that will never intersect

perpendicular lines

two lines that intersect (cross)

acute angle

an angle less than 90 degrees

right angle

an angle equal to 90 degrees

obtuse angle

an angle greater than 90 degrees

straight angle

an angle equal to 180 degrees

reflex angle

an angle greater than 180 degrees

vertex; more than one vertex is vertices

the point where lines connect; a "corner"

ordered pairs; coordinates

two numbers or letters that tell where on a grid a point is located on the x-axis and the y-axis.

origin

the point where the x-axis and the y-axis intersect; (0,0)