Geometry and Spatial Reasoning: Glossary

circle

From Grade 1

A round shape with no corners.

Learn it in: Circles (Grade 1), Shape patterns (Grade 1), Division using pictures (Grade 2)

corner

From Grade 1

Where two sides meet.

Learn it in: Circles (Grade 1), Triangles (Grade 1), Squares (Grade 1)

curved

From Grade 1

Bending like a rainbow, not straight.

Learn it in: Circles (Grade 1), Properties of 2D shapes (Grade 2)

round

From Grade 1

Shaped like a ball or a ring.

Full explanation with examples and practice →

Learn it in: Circles (Grade 1), Checking answers (Grade 2), Rounding to the nearest ten (Grade 3)

side

From Grade 1

A straight line that makes the edge of a shape.

Learn it in: Triangles (Grade 1), Squares (Grade 1), Properties of 2D shapes (Grade 2)

three

From Grade 1

The number 3.

Learn it in: Triangles (Grade 1)

triangle

From Grade 1

A shape with 3 straight sides and 3 corners.

Learn it in: Triangles (Grade 1), Shape patterns (Grade 1)

square

From Grade 1

A shape with 4 equal straight sides and 4 corners.

Learn it in: Squares (Grade 1), Shape patterns (Grade 1), Perimeter (Grade 4)

long side

From Grade 1

The longer side of a rectangle.

Learn it in: Rectangles (Grade 1)

opposite sides

From Grade 1

Sides across from each other.

Learn it in: Rectangles (Grade 1)

rectangle

From Grade 1

A shape with 4 straight sides and 4 square corners.

Learn it in: Rectangles (Grade 1), Perimeter (Grade 4)

short side

From Grade 1

The shorter side of a rectangle.

Learn it in: Rectangles (Grade 1)

cube

From Grade 1

A solid shape with 6 square faces.

Learn it in: Cubes (Grade 1), Surface area using nets (Grade 6)

edge

From Grade 1

Where two faces meet.

Learn it in: Cubes (Grade 1), Properties of 3D shapes (Grade 2), Spatial reasoning (Grade 6)

face

From Grade 1

A flat surface of a solid shape.

Learn it in: Cubes (Grade 1), Properties of 3D shapes (Grade 2), Spatial reasoning (Grade 6)

curved surface

From Grade 1

A surface that bends.

Learn it in: Spheres (Grade 1), Cylinders (Grade 1)

roll

From Grade 1

Turn over and over.

Learn it in: Spheres (Grade 1)

solid shape

From Grade 1

A shape you can hold, not flat.

Learn it in: Spheres (Grade 1), Identifying shapes in everyday life (Grade 1)

sphere

From Grade 1

A round solid shape, like a ball.

Learn it in: Spheres (Grade 1)

cylinder

From Grade 1

A solid shape with 2 flat circle faces and a curved side.

Learn it in: Cylinders (Grade 1)

flat face

From Grade 1

A flat surface.

Learn it in: Cylinders (Grade 1)

stack

From Grade 1

Put one on top of another.

Learn it in: Cylinders (Grade 1)

direction

From Grade 1

Which way to go.

Learn it in: Position and direction (Grade 1), Rays (Grade 4)

position

From Grade 1

Where something is.

Learn it in: Position and direction (Grade 1), Spatial reasoning (Grade 2), Points (Grade 4)

right

From Grade 1

The side opposite to left.

Learn it in: Position and direction (Grade 1)

describe

From Grade 1

Say what something is like.

Learn it in: Identifying shapes in everyday life (Grade 1), Identifying shapes (Grade 2)

flat shape

From Grade 1

A shape drawn on paper, like a circle.

Learn it in: Identifying shapes in everyday life (Grade 1)

object

From Grade 1

A thing you can see and touch.

Learn it in: Identifying shapes in everyday life (Grade 1), Identifying shapes (Grade 2)

2D shape

From Grade 2

A flat shape.

Learn it in: Properties of 2D shapes (Grade 2)

3D shape

From Grade 2

A solid shape.

Learn it in: Properties of 3D shapes (Grade 2)

vertex

From Grade 2

A corner of a solid.

Learn it in: Properties of 3D shapes (Grade 2), Sides and vertices (Grade 2), Polygons (Grade 3)

polygon

From Grade 2

A flat shape with straight sides.

Learn it in: Sides and vertices (Grade 2), Polygons (Grade 3), Two-dimensional figures (Grade 5)

vertices

From Grade 2

More than one vertex.

Learn it in: Sides and vertices (Grade 2)

clue

From Grade 2

A hint.

Learn it in: Identifying shapes (Grade 2)

identify

From Grade 2

Find out what something is.

Learn it in: Identifying shapes (Grade 2)

fold

From Grade 2

Bend over so edges meet.

Learn it in: Introduction to symmetry (Grade 2), Symmetry (Grade 3)

line of symmetry

From Grade 2

A fold line that makes two matching halves.

Learn it in: Introduction to symmetry (Grade 2), Symmetry (Grade 3), Symmetry (Grade 4)

mirror image

From Grade 2

The same shape reversed.

Learn it in: Introduction to symmetry (Grade 2)

symmetry

From Grade 2

Both sides match when folded.

Learn it in: Introduction to symmetry (Grade 2), Symmetry (Grade 3), Symmetry (Grade 5)

left and right

From Grade 2

Directions to your sides.

Learn it in: Spatial reasoning (Grade 2)

turn

From Grade 2

Move round a point.

Learn it in: Spatial reasoning (Grade 2)

closed

From Grade 3

No gaps.

Learn it in: Polygons (Grade 3)

equilateral

From Grade 3

All three sides equal.

Learn it in: Triangles (Grade 3), Classifying triangles (Grade 4), Triangles (Grade 5)

isosceles

From Grade 3

Two sides equal.

Learn it in: Triangles (Grade 3), Classifying triangles (Grade 4), Triangles (Grade 5)

scalene

From Grade 3

No sides equal.

Learn it in: Triangles (Grade 3), Classifying triangles (Grade 4), Triangles (Grade 5)

parallel

From Grade 3

Always the same distance apart.

Learn it in: Quadrilaterals (Grade 3), Properties of shapes (Grade 3), Parallel lines (Grade 4)

parallelogram

From Grade 3

Opposite sides parallel.

Learn it in: Quadrilaterals (Grade 3), Quadrilaterals (Grade 5), Quadrilaterals (Grade 6)

quadrilateral

From Grade 3

A polygon with 4 sides.

Learn it in: Quadrilaterals (Grade 3), Quadrilaterals (Grade 6)

rhombus

From Grade 3

4 equal sides.

Learn it in: Quadrilaterals (Grade 3), Quadrilaterals (Grade 5), Quadrilaterals (Grade 6)

property

From Grade 3

A feature of a shape.

Learn it in: Properties of shapes (Grade 3), Shape classification (Grade 3), Geometric reasoning (Grade 5)

angle

From Grade 3

Where two lines meet.

Full explanation with examples and practice →

Learn it in: Right angles (Grade 3), Angles (Grade 4), Two-dimensional figures (Grade 5)

right angle

From Grade 3

A square corner (90°).

Full explanation with examples and practice →

Learn it in: Right angles (Grade 3), Introduction to other angles (Grade 3), Perpendicular lines (Grade 4)

test

From Grade 3

Check with a paper corner.

Learn it in: Right angles (Grade 3)

acute angle

From Grade 3

Smaller than a right angle.

Learn it in: Introduction to other angles (Grade 3)

obtuse angle

From Grade 3

Bigger than a right angle but less than a straight line.

Learn it in: Introduction to other angles (Grade 3)

straight angle

From Grade 3

Makes a straight line (180°).

Learn it in: Introduction to other angles (Grade 3), Angles (Grade 6)

reflection

From Grade 3

A mirror image.

Learn it in: Symmetry (Grade 3), Symmetry (Grade 4), Plotting points in four quadrants (Grade 6)

Venn diagram

From Grade 3

Overlapping circles for sorting.

Learn it in: Shape classification (Grade 3)

arrow

From Grade 4

Shows the line continues.

Learn it in: Lines (Grade 4), Rays (Grade 4)

line

From Grade 4

A straight path that goes on forever both ways.

Learn it in: Lines (Grade 4)

points

From Grade 4

Positions on the line.

Learn it in: Lines (Grade 4)

straight

From Grade 4

No bends.

Learn it in: Lines (Grade 4)

endpoint

From Grade 4

The end of a segment.

Learn it in: Line segments (Grade 4), Rays (Grade 4)

line segment

From Grade 4

Part of a line with two endpoints.

Learn it in: Line segments (Grade 4), Points and lines (Grade 6)

ray

From Grade 4

Starts at one point and goes on forever.

Learn it in: Rays (Grade 4), Points and lines (Grade 6)

distance

From Grade 4

How far apart.

Learn it in: Parallel lines (Grade 4), Plotting points (Grade 5), Integers on number lines (Grade 6)

intersect

From Grade 4

Cross or meet.

Learn it in: Parallel lines (Grade 4), Perpendicular lines (Grade 4)

railway

From Grade 4

Two rails in parallel.

Learn it in: Parallel lines (Grade 4)

perpendicular

From Grade 4

Meeting at a right angle (90°).

Learn it in: Perpendicular lines (Grade 4), Points and lines (Grade 6)

set square

From Grade 4

Tool for right angles.

Learn it in: Perpendicular lines (Grade 4)

arm

From Grade 4

One of the rays.

Learn it in: Angles (Grade 4)

degree

From Grade 4

Unit of angle size (°).

Learn it in: Angles (Grade 4), Measuring angles (Grade 4)

baseline

From Grade 4

The 0° line.

Learn it in: Measuring angles (Grade 4)

protractor

From Grade 4

Tool for measuring angles.

Learn it in: Measuring angles (Grade 4)

right triangle

From Grade 4

Has a 90° angle.

Learn it in: Classifying triangles (Grade 4), Triangles (Grade 5)

regular polygon

From Grade 4

All sides and angles equal.

Learn it in: Symmetry (Grade 4), Properties of polygons (Grade 5), Perimeter (Grade 5)

symmetrical

From Grade 4

Both halves match.

Learn it in: Symmetry (Grade 4)

angle sum

From Grade 5

Total of the interior angles.

Learn it in: Properties of polygons (Grade 5), Triangles (Grade 6)

interior angle

From Grade 5

An angle inside a polygon.

Learn it in: Properties of polygons (Grade 5), Polygons (Grade 6)

irregular

From Grade 5

Not regular.

Learn it in: Properties of polygons (Grade 5)

kite

From Grade 5

Two pairs of adjacent equal sides.

Learn it in: Quadrilaterals (Grade 5)

trapezium

From Grade 5

One pair of parallel sides.

Learn it in: Quadrilaterals (Grade 5), Quadrilaterals (Grade 6)

coordinate grid

From Grade 5

Grid with two number lines.

Learn it in: Coordinate grids (Grade 5)

origin

From Grade 5

The point (0, 0).

Learn it in: Coordinate grids (Grade 5), Coordinate plane (Grade 6)

x-axis

From Grade 5

Horizontal axis.

Learn it in: Coordinate grids (Grade 5), Coordinate plane (Grade 6)

y-axis

From Grade 5

Vertical axis.

Learn it in: Coordinate grids (Grade 5), Coordinate plane (Grade 6)

ordered pair

From Grade 5

(x, y).

Learn it in: Plotting points (Grade 5), Plotting points in four quadrants (Grade 6)

plot

From Grade 5

Mark a point.

Learn it in: Plotting points (Grade 5)

rotational symmetry

From Grade 5

Looks the same after a turn.

Learn it in: Symmetry (Grade 5)

acute

From Grade 6

Less than 90°.

Learn it in: Angles (Grade 6)

obtuse

From Grade 6

Between 90° and 180°.

Learn it in: Angles (Grade 6)

vertically opposite

From Grade 6

Equal angles across a crossing.

Learn it in: Angles (Grade 6)

regular

From Grade 6

All sides and angles equal.

Learn it in: Polygons (Grade 6), Perimeter (Grade 6)

coordinate

From Grade 6

Number giving a position.

Learn it in: Coordinate plane (Grade 6)

negative coordinate

From Grade 6

Left or below zero.

Learn it in: Plotting points in four quadrants (Grade 6)

quadrant

From Grade 6

One of four regions.

Learn it in: Plotting points in four quadrants (Grade 6)

congruent

From Grade 6

Same size and shape.

Learn it in: Geometric properties (Grade 6)

diagonal

From Grade 6

Line joining opposite corners.

Learn it in: Geometric properties (Grade 6)

net

From Grade 6

Flat pattern of a solid.

Learn it in: Spatial reasoning (Grade 6), Surface area using nets (Grade 6)