9 hours Year 9 Extension Spring Term Unit 4 Geometrical reasoning: lines, angles and shapes; Construction

NNS 178–189, 194–197, 220–227

Autumn Term

Spring Term

Summer Term

Support (from Y9 teaching programme)
• Distinguish between conventions, definitions and derived properties
• Explain how to find, calculate and use (a) the sums of the interior and exterior angles of quadrilaterals, pentagons and hexagons, (b) the interior and exterior angles of regular polygons.
Solve problems using properties of angles, of parallel and intersecting lines, and of triangles and other polygons, justifying inferences and explaining reasoning with diagrams and text
• Find the locus of a point that moves according to a simple rule, both by reasoning and by using ICT

Core (from Y9 objectives for able pupils)
• Distinguish between practical demonstration and proof; know underlying assumptions, recognising their importance and limitations, and the effect of varying them
Know that if two 2-D shapes are similar, corresponding angles are equal and corresponding sides are in the same ratio
Understand and apply Pythagoras' theorem
• Know that the tangent at any point on a circle is perpendicular to the radius at that point; explain why the perpendicular from the centre to the chord bisects the chord
Know from experience of constructing them that triangles given SSS, SAS, ASA or RHS are unique, but that triangles given SSA or AAA are not; Apply these conditions to establish the congruence of triangles
• Find the locus of a point that moves according to a more complex rule, involving loci and simple constructions

 

Starters

Main

ICT

Scaffolding

Key Questions

Notes

1000 Playthinks
~ 260 Three intersecting circles
~ 261 Tangents to the circle
~ 266/268 Rolling coin 1 and 2
~ 271 Rolling circle: Hypocycloid
~ 286 Polygon Wheels
~ 307 Hidden triangle
~ 328 Inscribed square

ATM 40 Problems
~ p11 Toppling a square

ATM Thinkers p31
~ Put some geometrical statements in order which creates a proof

ATM Middles
~ Around the middle pl14

MAP

Pythagoras biography

 

Mymaths

Parallel Lines

Interior Exterior

Angle Proofs

Drawing Loci

Similar Triangles

Pythagoras: The Theorem

Pythagoras 3D

Circle Theorems

Congruent Triangles

Active worksheets

Various activities

Keymaths

9-3 Chapter 1, 12

ATM 40 Problems
~ p14 Inscribed and circumscribed circles

ATM Middles
~ Locus problem; Propellers; Triangle Constructions pl13; More imagining middles, pl11, Moving middles pl8

KS3
~ L3-L5, 9S1.1 Lines and angles L5
~ GR minipack

MAP
~ Circles investigations
~ 9 points on a circle
~ Compare relationships between the sides in acute / obtuse / right-angled triangles. (Sigma)

~ Locus Hocus Pocus

~ Gilbert the Goat
~ Square areas
~ Pythagorean triples

~ Pythagorean birthdays

 

GSP
Construct a triangle, then the squares on the sides of the triangle. Calculate areas of the squares. Demonstrate what particular triangles give one square to be the sum of the other two. What happens with acute angled and obtuse angled triangles?

LOGO~

Use Logo software to help with reasoning of interior/exterior angles

HORN, Cornwall
~ Overlapping circles
~ Pythagorean triples

KS3/ICT
~ Generalising about polygons

Using diagrams to support problem-solving - e.g. finding area of square with diagonal 10m, identyfing the link between the longest side and the largest angle of a triangle.

KS3 GR Minipack
~ Buildups

MAP
~ Generic assessment criteria

Is the hypotenuse always the sloping side?

 

How can we identify the hypotenuse?

 

Is the longest side always opposite the largest angle?

 

The hypotenuse of a right-angled triangle is 13cm. What are the other two sides? Is there more than one solution?

 

Are there any patterns in the Pythagorean triples? (See Pythagorean triples )

 

A square has a diagonal of length 5m. What is its area?

 

How can you make a right angle using a piece of string?

 

MAP – Level Ladders
~ Geometrical reasoning
~ Construction, loci

Extended tasks: Square areas ; Pythagorean triples
Group work
Written explanations
Oral explanations
Physical resources