Count : To count means to find out the number of objects by adding one for every object.

Length : Length is the attribute of a one-dimensional shape that can be measured with a measuring tape.

Parallel : Two lines in a two-dimensional plane are called parallel if they never cross.

Parallelogram : A parallelogram is a quadrilateral with 2 pairs of parallel sides. Rectangles, rhombuses and squares are special kinds of parallelograms.

Quadrilateral : A quadrilateral or quadrangle is a polygon with four corners. Rectangles, trapezoids, kites, rhombuses, squares and parallelograms are all specific kinds of quadrilaterals. The sum of the interior angles in a quadrilateral is always $360^{\circ}.$

Rectangle : A rectangle is a quadrilateral with 4 right angles. Two opposing sides in a rectangle have the same length. They are sometimes referred to as the width and the length of the rectangle. To calculate the area of an rectangle one can multiply the width of the rectangle by the length of the rectangle. A square is the special case of a rectangle in which all side lengths are the same. Every rectangle is a parallelogram.

Rhombus : A rhombus is a quadrilateral that has four equal length sides. Every rhombus is a parallelogram.

Shape : A shape is a set of points in space.

Square : A square is a quadrilateral with four right angles and four equal length sides. A square is a special case of a rectangle and a special case of a rhombus.

Equation : An equation is a mathematical statement in which two expressions are written with an equal sign in between. A solution of an equation is a set of variables that makes the statement a true statement.

Infinity : Infinity or $\infty$ represents a number that is bigger than all numbers in $\mathbb{R}.$

Solution : A solution to an equation is a choice of variables that when substituted into the equation results in a true statement.