understand how we use scale to draw accurate maps.
translate distances on maps to distances in the real world and vice versa.
use scale and griding to resize and recreate a cartoon.
various maps of different scales.
1. In this lesson, students will learn that maps are drawn to scale. They will learn how to use scale to read maps, and will be able to compare the kinds of information found on maps of different scale. Finally, they will redraw a cartoon they have brought from home using griding and scale to resize it.
Begin the lesson with two drawings on the board. You can draw whatever subject you choose, for example a tree or a star, but one drawing must be larger than the other, and they must be exactly to scale. The smaller of the two drawings should be smaller than letter size paper, the larger should be larger than letter size paper. Allow the class to look at the drawings, then ask them to tell you as much information as they can about the drawings: what is the same and what is different. Encourage the answers until you have a list that includes:
-They are both drawings of exactly the same object. -One is bigger than the other -They are in proportion to each other.
Next, hold up a piece of 8 ½ x 11 paper, and ask which of the drawings could fit on the paper and which could not.
Write the word “scale” on the board. Tell students that when cartographers make maps, they must represent extremely large items, such as continents, cities, and mountain ranges, on a small piece of paper. In order for maps to be useful, they must accurately represent the real world, including distances. Cartographers use scale to represent the real world on maps. A scale of 1:2 would mean that for every one unit on the map, there are two equal units in the real world. So, one centimetre on that map would be two centimetres in the real world. The map would be half the size of the object represented.
2. Distribute the maps evenly around the classroom. Ask students to look for the scales on the maps, and identify where they are found and how they are represented. Write the different scales on the board: 1:250 000, 1:100 000, 1:50,000 etc. Ask students to list what kinds of things are shown on maps of different scales. On which map are cities just a dot? On which map do you see individual streets? On which map do you see major rivers? On which map can you see creeks? Etc. Brainstorm what kinds of use maps of each different scale could be used for.
3. Do some scale translations together. Start with 1:100,000. Ask students how much distance would be represented by 1cm on the map. If they say 100,000 cm, let them know that that is a correct answer, but that we usually don’t talk about 100,000 cm. Rather, we discuss metres and kilometres. For example, we don’t see highway signs saying “279,592 cm to Vancouver, BC.” So, we convert the units.
If 100cm = 1m, then 100,000 cm = ? m
10,000 ) 100 = 1000m
1000 m = 1km
Therefore, we can discuss the scale 1:100,000 as 1cm = 1km
Now, try the scale 1:250,000 1:50,000 Etc.
Calculate for 1 cm and then for other distances.
4. Now, tell students that we often have to measure distances on maps that aren’t a straight line. To do this, we can get a close estimate by using a piece of thread to follow the route, and then measure the length of thread afterwards. Have students go back to the maps, and choose 5 different roads, rivers, or other routes. They will use the thread to measure, and then convert to real world distances. They will record their calculations on paper and hand them in for marking.
5. For classwork and homework, the students will resize a cartoon of their choice. They can choose to double it or use a different scale, but they must ensure that their drawing is exactly to scale. To do this, they will glue their cartoon to the top part of a second piece of paper, and then draw 1 cm grid lines overtop. They should label their grid lines ABC on the vertical and 123 on the horizontal. On the bottom of the paper, they draw a 2 cm grid, and label it the same way as the first. They then must draw the cartoon proportionately in the second grid.