B. People and Environments · Living and Working in OntarioMap Skills: Grids, Scale and Thematic Maps
B3.7 B2.3 B2.4About 40 minutes
Learning goals- I can find a place on a map using a grid, like B3.
- I can use a map scale to work out how far apart two places really are.
- I can tell what a thematic map shows by reading its title and legend.
- I can make my own map with a title, legend, compass rose, grid and scale.
Words to know
grid
Lines that cross to make squares on a map. Each square has a letter and a number.
grid reference
The letter and number that name one square, like B3.
scale
The part of a map that tells how a distance on the map matches a real distance on the ground.
kilometre (km)
A unit for measuring long distances. 1 kilometre is 1000 metres, about a 12 to 15 minute walk.
thematic map
A map that shows one topic, or theme, such as land use, landform regions or where people live.
Remember from Grade 1
In Grade 1 you drew maps with symbols and a legend, and you counted squares on a simple grid map. In Grade 2 you learned the four cardinal directions.
In Grade 3, mapmakers' tools get more exact. Today you will use grid references, a scale with real units (kilometres), and thematic maps.
Grids: a map's address system
A grid splits a map into squares. The columns going across have letters (A, B, C...). The rows going down have numbers (1, 2, 3...).
To name a square, say the letter first, then the number. B3 means column B, row 3. It is like saying "go across, then go down."
Worked exampleLet's use the grid together
Use the grid map above. In which square is the library? What is in square A4?
- Look at the legend: the library is a filled circle.
- Find the circle on the map. Go up from it to read the letter: C.
- Go left from it to read the number: 2.
- Now find A4: go to column A, then down to row 4. That square is filled in like the park box in the legend.
The library is in C2. Square A4 is the park.
Scale: how far is it really?
A map is much smaller than the real place. The scale tells us how much smaller.
Many maps show a scale bar. You line up a distance on the map with the bar to find the real distance.
For big places like Ontario, we measure in kilometres (km). A kilometre is 1000 metres. Walking 1 km takes most people about 12 to 15 minutes.
Worked exampleLet's measure with a scale
On a map, the scale says 1 cm on the map = 10 km on the ground. Two towns are 4 cm apart on the map. How far apart are they really?
- Each centimetre on the map stands for 10 km.
- There are 4 centimetres.
- Count by tens 4 times: 10, 20, 30, 40.
The towns are 40 km apart.
Thematic maps
Some maps show everything: roads, rivers, towns. Others show just one theme. These are thematic maps. Here are some examples:
- A land use map uses colours to show where there are homes, farms, factories and parks.
- A landform regions map shows the big areas of land that are alike.
- A population map shows where many people live and where few people live.
Always read the title and the legend first. They tell you the theme.
| Map title | What theme does it show? |
|---|
| Farms of Southern Ontario | where farms are (agriculture) |
| Ontario's Landform Regions | the big regions of land that are alike |
| Parks Near Our School | parks and green spaces (recreation) |
| Where People Live in Ontario | places with many people and places with few people |
Letter first, then number
A good way to remember the order: "Walk along the hall, then go up or down the stairs." Go across to the letter first, then down to the number.
Just for funRiddle: What has cities but no houses, forests but no trees, and lakes but no fish?
A map!
Hands-on activityMake a grid map of your kitchen or bedroom
You need: a big piece of paper, a ruler, a pencil, crayons and a grown-up helper.
- With the ruler, draw lines to make a grid of 4 columns and 4 rows. Label the columns A, B, C, D across the top and the rows 1, 2, 3, 4 down the side.
- Draw your room from above (a bird's-eye view). Use simple symbols: a square for a table, a circle for a lamp, and so on.
- Make a legend for your symbols.
- Add a title and a compass rose. (A grown-up can help you find north with a phone compass, or by remembering that the sun rises in the east.)
- Make a scale. Measure your room with your feet or a measuring tape. If your room is 4 metres wide and your map is 4 squares wide, then 1 square = 1 metre.
- Give a grown-up 3 grid references (like "C2") and see if they can find what is there.
What to look for: columns with letters, rows with numbers, a legend, a title, a compass rose and a scale.
Your turn
1Use the grid map. What is in square B3?
2Use the grid map. Give the grid reference for the lake.
3Use the grid map. Give the grid reference for the school.
4In a grid reference like C4, which comes first, the letter or the number?
The letter (the column) comes first, then the number (the row).
5A scale says 1 cm = 10 km. Two places are 3 cm apart on the map. How far apart are they?
30 km. 10 + 10 + 10 = 30.
A map that shows one topic or theme, like land use or landform regions.
7Use the scale bar picture. What real distance does the whole bar stand for?
More practice: warm-up
1How many metres are in 1 kilometre?
2What does a map's scale help you find out?
The real distance between places.
3A map is called Land Use in Our Town. What is its theme?
Land use: how the land in the town is used.
4Is a map bigger or smaller than the real place?
5Name the square that is in column A and row 1.
More practice: on your own
1A scale says 1 cm = 5 km. A lake is 6 cm long on the map. How long is it really?
30 km. Count by fives 6 times: 5, 10, 15, 20, 25, 30.
2Use the grid map. You walk from the house in B3 to the library in C2. Which way do you go? Use the compass rule that north is at the top.
You go north-east (up and to the right): one square east and one square north.
3Why do maps of Ontario use kilometres instead of metres?
Ontario is huge. Distances between towns are very long, so kilometres are easier to use than thousands of metres.
4Sam says the park is in square 4A. What should he say instead? Why?
A4. The letter (column) is said first, then the number (row).
5You want to show where all the farms, factories and homes are in your region. What kind of thematic map should you make?
A land use map, with a legend showing a colour or symbol for each kind of land use.
Challenge
1On a map, Toronto and Hamilton are about 6 cm apart. The scale is 1 cm = 10 km. About how far apart are they? Then explain how you would check if your answer makes sense.
About 60 km: 6 × 10 km = 60 km. To check, I could measure again or look up the driving distance with a grown-up. It is about 60 to 70 km by road, so my answer makes sense.
2Two maps show the same town. Map 1's scale is 1 cm = 1 km. Map 2's scale is 1 cm = 10 km. Which map shows the town bigger, with more details? Why?
Map 1. Each centimetre stands for a smaller real distance (1 km), so the town is drawn bigger, with room for streets and buildings. Map 2 squeezes 10 km into each centimetre, so the town looks tiny.
3Make up a grid reference question for a friend using the grid map above, and give the answer.
Model answer: "What is in C2?" Answer: the library. (Any question works if the letter-then-number reference matches the map.)
Quiz
1. In the grid reference B3, what does the B tell you?
2. A scale says 1 cm = 10 km. Two towns are 5 cm apart on the map. How far apart are they?
3. What does a thematic map show?
4. How many metres are in 1 km?
5. Which part of a map should you read first to know what it is about?
6. Use the grid map in this lesson. What is in square D1?
Big idea: Maps use a grid to name locations (letter for the column, number for the row), a scale to show real distances in standard units such as kilometres, and a title and legend to explain their theme. In this unit, students also make maps that show land use, landform regions and municipalities in Ontario.
How to help at home:
- Many road maps, mall maps and park maps have grids. Ask your child to find a place using the index ("the arena is in C4").
- Use a map app with a grown-up and turn on the scale bar. Ask, "About how many kilometres is it to Grandma's house?"
- Connect to math: Grade 3 students skip count by 2s, 5s and 10s, which makes scale questions easier.
Common difficulties:
- Reversing grid references (saying 3B). Practise "across, then down."
- Measuring from the wrong spot. Remind your child to start at 0 on the ruler or scale bar.
- Thinking a thematic map shows everything. Ask, "What is the theme? What is left out?"