Use the definitions in this glossary of math terms to help you talk about math ideas with your child.

**Angle:**the V-shaped figure formed by two lines meeting at a point (angle shape); or, the measure of the turn formed by two lines meeting at a point (angle measure).

**Attribute:**a detail, such as size, shape, or color, used to describe an object.

**Area:**the number of square units that fit inside a two-dimensional shape (like a rectangle), or that cover a surface of a three-dimensional shape (like a cube).

**Bar Graph:**a graph where the length of a bar represents a certain amount.

**Circle:**a two-dimensional round shape where every point on its boundary is the same distance from the center.

**Circumference:**the distance around a circle.

**Cube:**a three-dimensional solid shape with 6 identical square faces.

**Cylinder:**a three-dimensional solid shape with identical circular ends (a can).

**Estimation:**an educated ‘guess’; a rough calculation.

**Geometry:**the mathematics of points, angles, lines, surfaces, flat shapes and solids.

**Graph:**a drawing or diagram that shows the relationship between numbers using pictures, bars, or lines.

**Line:**a collection of points forming a straight path extending in two directions.

**One-to-One Correspondence:**the matching of one thing to another; for example, the matching of the number “3” to three bears, or “4” to moving forward four spaces on a board game.

**Parallel:**lines that are always the same distance apart and never intersect.

**Pattern:**a design or sequence that repeats itself in a predictable way.

**Probability:**the numerical chance that a specific outcome will occur.

**Pyramid:**a three-dimensional shape with a square or triangular base and triangular sides that come together in a point.

**Rectangle:**a two-dimensional, four-sided shape with two pairs of equal-length, parallel sides and four right angles.

**Spatial Reasoning Skills:**the ability to figure out how two-dimensional flat shapes or three-dimensional solid shapes may fit together to create new shapes.

**Square:**a two-dimensional, four-sided shape with equal-length sides and four right angles.

**Statistics:**the mathematics of collecting and analyzing data to draw conclusions and make predictions.

**Symmetry:**an attribute of a figure where one part of it fits exactly onto itself, as when something can be folded along a line so the two halves match exactly.

**Tally:**a way to keep track when counting by making marks or using counters.

**Tessellation:**a design of repeating shapes that fit together without gaps or overlaps.

**Triangle:**a two-dimensional, three-sided shape with three angles.

**Volume:**how much a container holds, or the amount of space occupied by a three-dimensional object.