# Lesson Notes By Weeks and Term - Senior Secondary 1

Map distance, reduction and enlargement

TERM – 2ND TERM

WEEK TEN

Class: Senior Secondary School 1

Age: 15 years

Duration: 40 minutes of 5 periods each

Date:

Subject: Geography

Topic: MAP DISTANCE, REDUCTION AND ENLARGEMENT

SPECIFIC OBJECTIVES: At the end of the lesson, pupils should be able to

1. Explain the procedures for measuring distance
2. Convert distances on a map to actual ground distance.

INSTRUCTIONAL TECHNIQUES: Identification, explanation, questions and answers,

demonstration, videos from source

INSTRUCTIONAL MATERIALS: Videos, loud speaker, textbook, pictures

INSTRUCTIONAL PROCEDURES

PERIOD 1-2

 PRESENTATION TEACHER’S ACTIVITY STUDENT’S ACTIVITY STEP 1 INTRODUCTION The teacher explain the meaning of map distance to the students Students as a whole, describe the procedures for measuring distances on the map STEP 2 EXPLANATION Teacher provided a map, measures and calculate distances on it Students on their own measures and calculate given distances on a map STEP 3 DEMONSTRATIO N Teacher show the students how to convert distances on a map to actual ground distance. Students on their own convert map distance to actual ground distance. STEP 4 NOTE TAKING The teacher writes a summarized note on the board The students copy the note in their books

NOTE

MAP DISTANCE, REDUCTION AND ENLARGEMENT

Map distance: Map distance refers to the physical distance between two points on a map. It's the measurement of how far apart locations are represented on the map, typically in units like kilometers or miles. There are two types of distance that can be measured on the map.

1. Measurement Of Straight Line Distances

This is the measurement of distance between two places on a straight line. A straight line

This straight-line distance between two locations on a map is often called "as the crow flies".

Procedure

1. Identify the starting and ending points on the map.
2. Place a straightedge (like a ruler or a piece of paper) between the two points, aligning it with the desired direction.
3.  Use the map's scale to determine the distance represented by the straightedge. If the scale is in miles or kilometers, measure the distance along the straight line.
4. If the scale is in a different unit than you prefer (e.g., inches on the map, but you want the distance in miles), convert the measurement accordingly.

Example 1 : Calculate the distance as the crow flies from point A to point B.

The distance between A and B = 7cm

The scale of map = 1:100,000 or 1cm to 1km

Now if 1cm to 1km on the Map,

7cm = 7cm x 100,000/ 100, 000

= 7 km

Therefore, 7cm measured on the map at point A and B is 7km on actual ground.

2. Measurement Of Curve distance

Curve distance include roads, railway, rivers etc. These are distances that are

not straight.

Procedure

1.Use of a pair of divider: To use this method, break the distance into small sections from one bend to another. Use a pair of dividers to measure each short stretch and then determine the distance in centimeters from your ruler. Add up all the sections together and relate it to the scale of the map

2.Use a thread: Stretch a piece of white thread along the route or curve to

be measured and carefully follow all the curves or bends. Mark the end of the

distance on the thread with a pen and transfer to a ruler in order to get the

actual distance on the map between the two places. Relate the distance

obtained to the scale of the map extract to determine the actual distance on the

ground.

Example 2:  Imagine the curve on the male below, calculate the distance from the beginning of the curve to the end.

Scale given: 1cm to 2 km

Solution

Using thread to measure the length of the distance and relate it to ruler, you

have 10cm.

Now  10 cm to the scale of the map = 1cm to 2km = 10/1 X 2km=20km

Hence, 10cm measured on the map is 20km on ground.

Conversion from Map Distance to Actual Distance

To convert map distance to actual distance, you need to know the scale of the map. The scale is usually given as a ratio, like 1:50,000. This means that 1 unit on the map corresponds to 50,000 of the same units in reality. Multiply the map distance by the scale to find the actual distance. For example, if the map scale is 1:50,000 and you measured 2 centimeters on the map, the actual distance would be 100,000 centimeters or 1 kilometer.

Example1: If the map distance is 8cm and the scale of the map is 1: 200,000. Calculate the actual distance on ground using either RF or statement of scale.

Solution:

R.F Scale: 1:200, 000.  Statement Scale: 1cm to 2km

8cm = 8 X 200,000 / 100,000

8cm = 8 X 2km = 16km

Therefore the actual distance on ground is 16km when the map distance is 8cm

Conversion from Actual Distance to Map Distance.

Example 2: If the ground distance between two places is 20km, what will be the map

distance if the scale of the map is 1cm to 1km?

Solution:

Ground distance = 20km

Map scale = 1cm to 1km

Since 1cm =1km, Map distance = 20cm

EVALUATION: 1. What is map distance.

1. If the map distance is 12cm and the scale of the map is 1:300,000, calculate the ground distance.
2. Calculate the map distance if the ground distance is 40km and the map scale is 1:200,000.

CLASSWORK: As in evaluation

CONCLUSION: The teacher commends the students positively