GEOMETRY
Triangles

Right Triangle - Has one right angle (90 degrees)

Acute triangle - all angles are less than 90 degrees

Obtuse triangle - has one angle that is bigger than 90 degrees

These triangles right triangle, acute triangles, and obtuse triangles are all similar they are all about angles.

Equilateral triangle - Three equal sides

Isosceles triangle - two equal sides

Scalene triangle - no equal sides

These triangles scalene, isosceles, and equilateral are all similar because they are all about the sides.

Websites used : www.mathisfun.com

Cool games and videos
http://www.khanacademy.org/math/cc-fourth-grade-ma...