Geometry is a popular topic of late on several groups of which I am part - both Montessori and non-Montessori.
At primary, we give the children the names of the shapes (plane and solid), and we give some basic parts such as parts of a triangle, so they become familiar with angles and such.
In elementary, we go much deeper with it because the child has had a lot of experience, has the vocabulary, and now wants to know definitions and origins - and connections between all things.
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I thought I would share the "table of contents", if you will, for the elementary nomenclature material as I have them in my Montessori albums. Different sets are available, which are also great for use; this is just what I have :)
Each letter/number is a booklet, with a packet of 4-part cards (name, definition, picture (use the booklet as control))
The title is listed follow by (the contents in parentheses)
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A1: Point to a Solid (point, line, solid, surface)
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B - Lines
B1: Types of Lines (straight, curved)
B2: Parts of a straight line (origin, line segment, ray, end points, line)
B3: Positions of a straight line (horizontal straight line, vertical straight line, oblique straight line)
B4: Position of 2 straight lines (convergent straight lines, perpendicular straight lines, parallel straight lines, divergent straight lines)
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C -Angles
C1: Angle and its parts (angle, size, sides, vertex)
C2: Types of Angles (obtuse, right, straight, acute, whole)
C3: Relationship between 2 angles (adjacent, vertically opposite, linear pair)
C4: 2 Particular Combination of angles (complementary, supplementary)
C5: Angles formed by 2 straight lines cut by a transversal (exterior, interior, alternate interior, alternate exterior, corresponding)
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D - Plane Figures
D1: Types of Plane Figures (polygon, simple, closed, curved)
D2: Plane figures bounded by line segments (triangle, polygon, quadrilateral)
D3: Plane figures bounded by curved lines (ellipse, oval, circle)
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E - Triangles
E1: Types of triangles according to sides (isosceles, scalene, equilateral)
E2: Types of triangles according to angles (acute-angle, obtuse-angle, right-angle)
E3: Parts of triangles (surface, sides, base, perimeter, vertex, altitude, angle)
E4: Sides of right angled triangles (hypotenuse, legs)
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F - Quadrilaterals
F1: Types of Quadrilaterals (parallelogram, rectangle, trapezoid, rhombus, square, common quadrilateral)
F2: Parts of the basic parallelogram (surface, sides, base, perimeter, vertices, altitude, angle, diagonal)
F3: Parts of the rectangle (base, diagonal, sides, vertices, surface, altitude, angle, perimeter)
F4: Parts of the rhombus (diagonal, angle, altitude, vertices, perimeter, base, sides, surface)
F5: Parts of the square (diagonal, angle, altitude, vertices, perimeter, base, sides, surface)
F6: Parts of the trapezoid (vertices, perimeter, angle, oblique sides, surface, bases, major base, minor base, altitude, diagonal)
F7: Types of trapezoids (scalene trapezoid, right-angled trapezoid, isosceles trapezoid)
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G - Polygons
G1: Types of polygons (irregular, regular)
G2: Types of regular polygons (equilateral, square, pentagon, hexagon, heptagon, octagon, nonagon, decagon)
G3: Parts of the polygon (surface, sides, perimeter, vertices, angle, diagonal, center, radius, apothem)
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H - Circles
H1a: Parts of a circle I (radius, diameter, chord, surface, center, circumference)
H1b: Parts of a circle II (semi-circle, semi-circumference, arc segment, sector)
H2: Relative positions between circumference and a straight line (external, secant, tangent)
H3: Relative positions between 2 circles (external, internal, externally tangent, internally tangent, secant, concentric)
(I have also seen annulus included here - but question if it belongs here - it is more likely to belong in a booklet discussing the parts of two circles in position with one another)
