Angle : If two line segments (or rays) both start at a common point the opening between the two line segments is called an angle. The common point is called vertex of the angle. The size of an angle is measured in degrees.

Corner : A corner of a shape is a point in the shape such that this point does not lie on the line segment between any two other points in the shape. Every triangle has 3 corners and every quadrilateral has 4 corners.

Number : A number $x$ is a mathematical symbol representing a quantity.

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 $360^{\circ}.$

Number : A number $x$ is a mathematical symbol representing a quantity.

Area : The amount of unit squares that is needed to cover a 2-dimensional shape.

Base : When using the height of a triangle or parallelogram (for example in an area calculation), base refers to the side of the triangle or parallelogram that the height starts out at. In a logarithm $\log_{b}x$ or power $b^x$ base refers to the number $b.$

Centimeter : A centimeter ($cm$) is $\frac{1}{100}$ of a meter.

Height : In a triangle a height (or altitude) is the shortest line segment that connects a side to its opposing corner. A height of a triangle is perpendicular to the side is started at. The three heights of a triangle intersect in a point, the so called orthocenter of the triangle. In a parallelogram the height is the shortest distance between two opposing sides. In a pyramid the height is the shortest distance between the base area and the corner of the pyramid that is not part of the base area. In a prism the height is the shortest distance between the two base faces.

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

Square centimeter : Square centimeter or $cm^2$ is a unit of measurement for measuring area. 1 square centimeter is the area of a square with side length 1 $cm,$ so 10,000 $cm^2$ are one $m^2.$