Mathematics 2D Shapes

Aims of the Lesson To learn most of the keywords associated with shapes and angles. To recognise the 4 main basic 2D shapes. To recognise the 3 types of triangle and learn to given them their full mathematical name. To recognise and name the 6 main types of quadrilateral.

Keywords Save and printout ShapeKW.docx Separate the table at the top from the descriptors at the bottom which should be separated by cutting along the lines. As you progress through the next few slides, you will be able to match the descriptor with its keyword and stick it into the table.

Keywords – lines A line which always travels in the same direction without bending is straight, but a line deviating from the straight in a smooth way is curved. A line which is lying flat is horizontal, whilst a line which is standing upright is vertical. Lines that meet at right angles are perpendicular. Lines that are always the same distance apart and therefore always travelling in the same direction together are parallel.

Keywords – 2D shapes Any 3-sided flat (2D) shape is called a triangle. Any 4-sided flat (2D) shape is called a quadrilateral. All other flat (2D) shapes with ‘many’ sides are called polygons. If a shape’s sides are all the same length AND all its angles are equal, then it is a regular shape.

Keywords – 3D shapes A 3D shape with many triangular faces is called a polyhedron. The corner of a 3D shape is called a vertex (plural of this is vertices). The flat side of a 3D shape is called a face. Where two flat sides meet, they form an edge.

Lead-In As a lead into the next part of the lesson please work through the MyMaths lesson called: Shape > 2D and 3D Shapes > 2D and 3D Shapes It can be found at this URL: http://app.mymaths.co.uk/241-resource/2d-and-3d-shapes

Types of Triangle A triangle with 3 equal sides and 3 equal angles is called an equilateral triangle. It will also have 3 lines of symmetry and rotational symmetry of order 3.

Types of Triangle A triangle with 2 equal sides and 2 equal angles is called an isosceles triangle. It has 1 line of symmetry which folds one of the equal sides and angles over on to the other side.

Types of Triangle A triangle with no equal sides or equal angles is called a scalene triangle. It has no lines of symmetry or rotational symmetry.

Naming triangles At KS3 you only have to name a triangle using the terms equilateral, isosceles or scalene (followed by the word triangle). At KS4, if it is an isosceles or scalene triangle you should also find the largest angle and write the angle type in front of the type of triangle.

Examples This triangle has two sides marked as being equal. KS3: It is an isosceles triangle The largest angle is here and is clearly larger than a right angle so… KS4: It is an obtuse-angled isosceles triangle This triangle has 3 angles marked as being equal. KS3: It is an equilateral triangle KS4: It is an equilateral triangle This triangle has no sides or angles marked as equal (although it does have one right angle marked). KS3: It is a scalene triangle The largest angle is the right angle (as the other two angles are both acute) so… KS4: It is a right-angled scalene triangle

Lead-In As a lead into the rest of the lesson please work through the MyMaths lesson called: Shape > 2D and 3D Shapes > Lines and Quadrilaterals It can be found at this URL: http://app.mymaths.co.uk/245-resource/lines-and-quadrilaterals

Types of Quadrilateral This is a RECTANGLE. It has 2 pairs of equal sides. It has 4 equal angles (all 90°). It has 2 pairs of parallel sides. It has 2 lines of symmetry and rotational symmetry of order 2.

Types of Quadrilateral This is a SQUARE. It has 4 equal sides. It has 4 equal angles (all 90°). It has 2 pairs of parallel sides. It has 4 lines of symmetry and rotational symmetry of order 4. It’s diagonal lines cross at 90°.

Types of Quadrilateral This is a PARALLELOGRAM (it looks like a tilted rectangle). It has 2 pairs of equal sides. It has 2 pairs of equal angles (opposite angles are equal). It has 2 pairs of parallel sides. It has 0 lines of symmetry but rotational symmetry of order 2.

Types of Quadrilateral This is a RHOMBUS (it looks like a tilted square). It has 4 equal sides. It has 2 pairs of equal angles (opposite angles are equal). It has 2 pairs of parallel sides. It has 2 lines of symmetry and rotational symmetry of order 2. It’s diagonal lines cross at 90°.

Types of Quadrilateral This is a KITE. It has 2 pairs of equal sides. It has 1 pair of equal angles. It has NO parallel sides. It has 1 line of symmetry. It’s diagonal lines cross at 90°.

Types of Quadrilateral This is a TRAPEZIUM. It has 1 pair of parallel sides. Sometimes you will come across an ISOSCELES TRAPEZIUM which also has… 1 pair of equal sides 2 pairs of equal angles and 1 line of symmetry

What next? Print out the notes called Shape1-2D.docx. Read through them and make sure you answer any questions. You can always review the powerpoint or any of the MyMaths lessons again to help you. Now move on to the Angle1-Types powerpoint