Relationships and Change - Week 47 - Lesson 2 - Using ratios with map scales + Introduction to Proportion
Objective (Teaching Point): Using ratios with map scales. Starter: Solve the following problems and reduce answers to simplest terms without units: (a) 3 feet : 6 inches (b) 25 / 80 (b) 25 lb cement : 50 lb sand : 75 lb crushed rock LESSON Give me some scales that we use in maps. 1 : 50 000 Every cm represents 50 000 cm = 500 m = 0,5 km 1 : 100 000 Every cm represents 100 000 cm = 1000m = 1 km 1cm : 5km Every cm represents 5km 1cm : 10m Every 1cm represents 10m. Exercise in Class Calculate the actual distances that are represented by the following lengths on the map. A map has an actual scale of 1cm : 500m 3cm 8cm 13cm 0,5cm or 5mm 0,1cm or 1mm Introducing Direct Proportion: Example 1:- If a can of cola costs 20kr; how much is the cost of: 2 cans 5 cans 10 cans 11 cans Question 1:- 1 Litre of Petrol costs 8,3kr; How much will you pay for: 2 litres 5 litres 10 litres 20 litres Example 2:- If 120 calculators cost 1700 kr. How much will you pay for:- 1 calculator 5 calculators 7 calculators Question 2:- If 5 cinema tickets cost 400kr. How much will you pay for:- 1 cinema ticket 4 cinema tickets 9 cinema tickets Question 3:- If 3 glasses can fill up to 600ml of water. How much water can you fill in:- 7 glasses 9 glasses