Wolfram Research
Wolfram Math World: Squares
MathWorld provides multiple definitions and formulas for the mathematical term, square.
Illustrative Mathematics
Illustrative Mathematics: 6.ee Rectangle Perimeter 3
The purpose of this task is to ask students to write expressions and to consider what it means for two expressions to be equivalent. Aligns with 6.EE.A.
CK-12 Foundation
Ck 12: Geometry: Parallelograms
[Free Registration/Login may be required to access all resource tools.] This concept teaches students properties of and theorems about parallelograms and how to apply them.
CK-12 Foundation
Ck 12: Geometry: Parallelograms
[Free Registration/Login may be required to access all resource tools.] Apply parallelogram theorems.
Quia
Ixl Learning: Trapezoids
Brush up on your math skills relating to trapezoids then try some practice problems to test your understanding.