Lesson Notes By Weeks and Term v5 - Grade 10

Lesson Video

This page supports the lesson note with a companion video and a short classroom-ready summary.

For class groups and homework, share this lesson page so learners also get the summary, objectives, and full lesson context.

Performance objectives

• Calculate distances using scale on maps and plans.
• Determine direction using compass directions and bearings.
• Interpret symbols and keys on maps and plans.
• Use grid references to locate specific places.
• Calculate area from scale drawings.

Lesson summary

This week, we delve deeper into maps, plans, and other visual representations of the physical world. Understanding these representations is crucial because they allow us to navigate our surroundings effectively, interpret spatial information, and make informed decisions related to location, distance, and scale. From reading street maps to understanding building plans or interpreting satellite imagery of South Africa's diverse landscapes, these skills are essential for everyday life and various careers.

Lesson notes

Scale: The scale of a map or plan is the ratio that represents the relationship between a distance on the map and the corresponding distance on the ground.

It's expressed in several ways: Ratio Scale: e.g., 1:50,000 (1 cm on the map represents 50,000 cm in reality)

Verbal Scale: e.g., "1 cm represents 1 km" Graphic Scale (Bar Scale): A line divided into segments, representing real-world distances. Understanding scale is paramount. Incorrect use of scale leads to inaccurate distance or area calculations. Remember that 1 km = 1000 m and 1 m = 100 cm.

Example: A map has a scale of 1:20,

0

0

0. Two landmarks are 8 cm apart on the map. What is the actual distance between them?

Solution: The scale 1:20,000 means 1 cm on the map represents 20,000 cm in reality. Real distance = Map distance × Scale factor = 8 cm × 20,000 = 160,000 cm Convert cm to meters: 160,000 cm ÷ 100 = 1600 m Convert meters to kilometers: 1600 m ÷ 1000 = 1.6 km Therefore, the actual distance between the landmarks is 1.6 km.

Direction and Orientation: Maps use compass directions (North, South, East, West) and bearings to indicate direction. A bearing is an angle measured clockwise from North. Understanding direction is critical for navigation. Consider the impact of taking the wrong direction while travelling in a rural area; it can lead to getting lost.

Example: On a map, town B is located South-East of town

A. What does this mean in terms of relative location?

Solution: Town B is located both south and east, in a direction of roughly 45° southeast, relative to town

A. This gives a general idea of its position.

Example: A hiker uses a compass and finds that a particular landmark is at a bearing of 135° from their current location. What direction is the landmark from the hiker?

Solution: A bearing of 135° is South-East (90° is East, 180° is South. 135 is halfway between).

Symbols and Keys (Legends): Maps use symbols to represent various features like buildings, roads, rivers, hospitals, and schools. A key (or legend) explains what each symbol represents. Being able to read a map's legend is essential. Imagine using a map with symbols you don't understand: you may mistake a clinic for a school, potentially causing confusion and delays.

Example: A map legend shows a small blue line representing a river. What does this indicate on the map?

Solution: The blue line indicates the presence of a river at that location on the ground.

Grid References: A grid reference is a system of lines (usually numbered or lettered) that divide a map into squares, allowing for precise location identification. Grid references usually use a combination of letters and numbers (e.g., A3, B7). Remember to read "across" before "up". This helps in uniquely identifying any square on the grid.

Example: A map has a grid system. A specific school is located in grid square C

4. Describe how to find the school on the map.

Solution: Locate the vertical line labeled "C" and the horizontal line labeled "4." The school is located within the square where these two lines intersect.

Area Calculation from Scale Drawings: Scale drawings are used in architecture and design to represent buildings or objects proportionally. To calculate the actual area from a scale drawing, you must first convert the dimensions of the drawing to their actual lengths and widths using the scale.

Example: A floor plan of a rectangular room is drawn to a scale of 1:

5

0. The length of the room on the plan is 10 cm, and the width is 6 cm. What is the actual area of the room in square meters?

Solution: Convert plan lengths to real lengths using the scale: Real Length = 10 cm × 50 = 500 cm = 5 m Real Width = 6 cm × 50 = 300 cm = 3 m Calculate the actual area: Area = Length × Width = 5 m × 3 m = 15 m² Therefore, the actual area of the room is 15 square meters. Guided Practice (With Solutions)

Question 1: A map has a scale of 1:100,

0

0

0. The distance between Johannesburg and Pretoria on the map is 5 cm. Calculate the actual distance between the two cities in kilometers.

Solution: Real distance = Map distance × Scale factor = 5 cm × 100,000 = 500,000 cm Convert cm to meters: 500,000 cm ÷ 100 = 5,000 m Convert meters to kilometers: 5,000 m ÷ 1000 = 50 km Therefore, the actual distance between Johannesburg and Pretoria is 50 km.

Question 2: A map shows a hospital located in grid square D6 and a police station in grid square A

2. Describe the process of finding these locations on the map. Also determine which location is relatively further up/North on the map.

Solution: To find the hospital, locate the vertical line labeled "D" and the horizontal line labeled "6." The hospital is located within the square where these two lines intersect. To find the police station, locate the vertical line labeled "A" and the horizontal line labeled "2." The police station is located within the square where these two lines intersect. Square D6 is below/South of A2, therefore the Police station is further up/North.