 Calculate:  Perform mathematical operations

 Calculator:  A device used to perform mathematical operations 
 Capacity:  The amount a container can hold 
 Carroll diagram:  A sorting diagram named after Lewis Carroll 
 Cartesian plane:  Also called the coordinate plane. Contains two perpendicular axes  XAxis and YAxis. Points are plotted taking a position from both the x and y axis. eg (3,10) 
 Chord:  A line segment connecting two point on a circles perimiter. 
 Circle:  A plane shape drawn by a line whose points are equidistant from the centre point of the circle. 
 Circumference:  The distance around the circle. Calculated by: C = 2.Pi.r 
 Clockwise:  The direction the hands on an anologue clock move. 
 Closed Curve:  Any curve where it joins itself at its starting point. 
 Cointerior angles:  The inner angles on the SAME side of a line drawn through parallel lines 
 Colinear:  When objects are situated on the same line. 
 Colinear points:  Three or more points that lie on the same line. 
 Compass (construction):  An instrument used to create circles. 
 Complimentary angle:  Two angles whose sum EQUALS 90 degrees 
 Concave:  Curved inwards. The opposite of convex. 
 Concave quadrilateral:  A quadrilaterl with at least one reflex angle. 
 Concave Polygon:  Any polygon with at least one reflex angle. 
 Concentric Circle:  Circles different in size, but share a center point. 
 Cone:  A solid shape composed of an circular or eliptical base, and a curved surface which tapers to a vertex. 
 Congruent figures:  A congruent figure has all equal sides and all equal angles. 
 Converging lines:  Lines that all head in the direction of the same point. 
 Convex:  Curved outwards  the oposite of concave. 
 Convex Quadrilaterals:  A quadrilateral where no angles are greater than 180 degrees (reflex) 
 Coordinates:  Pairs of letters or numbers indicating a points position on the cartesian/coordinate plane. They are always indicated with the xaxis value first, then the yaxis. eg (4,7) 
 Coordinate plane:  Same as Cartesian Plane 
 Coplanar:  Geometric objects that exist on the same plane. 
 Corner:  The points where surfaces/vertices meet. 
 Corresponding angles:  Angles that have the same position created by one line intersecting two or more paralell lines. 
 Counter Clockwise:  Same as anti clockwise. 
 Cross Section:  The face that results when a solid shape is cut. 
 Cube:  A solid shape whose form is created by 6 congruent squares. Also one of the 5 Platonic Solids. 
 Cubic:  The term used when describing a unit of volume. 
 Cuboid:  A right prism created by six rectangular faces. If all faces are square it is called a cube. 
 Curve:  A line that is NOT straight. 
 Cyclic Quadrilaterals:  A quadrilateral where a circle can be circumscribed to contain all four vertices. 
 Cylinder:  A solid shape composed of two congruent circles and one curved surface. 
 Deca:  Prefix meaning 10 
 Decagon:  A 10 sided polygon. 
 Decahedron:  A Polyhedron with 10 faces. 
 Decrease:  To make smaller in size. 
 Deduct:  To subtract or take away. 
 Degree (angle):  The unit which angles are measured by. 
 Diagonal:  A line joining two NONadjacent vertices. 
 Diameter:  A line connecting two points of a circle, which also includes the centre point of the circle. 
 Diamond:  A plane shape with 4 equal sides and NO right angles. Also known as a Rhombus. 
 Distance:  The length between two points or objects. 
 Divisible:  Can be divided without a remainder. 
 Dodeca:  Prefix for 12. 
 Dodecagon:  A polygon with 12 straight edges. 
 Dodechedron:  A Polyhedron with 12 faces. 