This lesson will explain what a scale map is and how it represents two different things on the map expressed as a ratio. This lesson will also demonstrate the steps needed to create a scale map from any ordinary map.
A Scale Disaster
Once there was a king who needed to build a stable for his daughter's new horse. She had recently outgrown the pony she had been given as a child and needed a proper steed. To keep the gift a surprise, the king hid the new horse and had a stable made from measurements he took himself. Heel-to-toe, he walked out the distance. The stable was to be 20 steps long and 10 steps wide. He sent his best carpenter the measurements to have a stable built at the castle in preparations for the gift.
But when the princess noticed a new stable being built, she was sad because it was a small stable, and she had truly hoped for a larger horse. This stable was only big enough for another small pony. When the time came and the horse was finally brought out of hiding, the princess was instantly glad again, realizing it was much bigger than the pony she already had.
The king was confused and asked the carpenter what had happened. That was when he noticed the carpenter's small feet. The measurements from the king had been made with his much larger foot, and the stable had been built by the carpenter with tiny little feet. The carpenter set at once to make a larger stable.
While this story may seem childish, it actually conveys a very interesting point. How big are things when we measure them? For instance, when you look at a map, things are much smaller and closer together than we know they actually are. If the map only showed that grandma's house is three inches away, then why does it take nine hours to get there?
This lesson will focus on something called a scale map, how to read them and how to make your own.
How Scale Maps Work
Typically, scale maps work like this: in the corner of the map, there will be something called a scale. A scale is actually just a ratio of two numbers. So, a scale map is just a map that contains a scale on it. Pretty simple, huh?
The first number relates to the map. The second is the corresponding place that the map actually portrays. The ratio will look something like this: 1:18,000. The way you read this is 1 to 18,000. You can think of it as saying one of something on the map is equal to 18,000 of that exact same thing in the real location. A scale map takes one item and tells how many of the same item would be needed in the real world to make the actual distance.
This is different from something called a bar scale, which is a line on the bottom of some maps that shows a distance on that particular map.
For example, if we look back at our map, this means that one of anything placed on the map is equivalent to 18,000 of the same thing in real life. So if I tell you the distance on the map from A to B is one inch, we can start making some headway.
Distance between points A and B
From what we already know about scale, that means that the true distance from A to B must actually measure 18,000 inches in real life. Remember that 1:18,000 means that 1 inch on the map is actually 18,000 inches in real life.
However, since we don't normally measure large distances with such a small unit, it would be a bit like using a tiny ruler to measure the distance to your neighboring city. But we can convert these units into something more recognizable. If you were to divide 18,000 by 12, that would be how many feet it represents instead of inches because there are 12 inches in a foot. This would be 1,500 feet; a more manageable number.
The scale is still the same, 1:18,000, but you could also say that 1 inch on this map is equal to 1,500 feet, which is really still the same as 18,000 inches. You do this type of conversion all the time when you tell someone how tall you are in feet instead of inches. If you were 66 inches tall, you would also be 5 feet, 6 inches high. Both numbers are the same height; you just converted to different units.
Oh, I want to demonstrate the best part of this type of map. You don't even have to have a special tool to measure how long something is! You can use anything to measure with, maybe you have a pen or an old shoelace laying around. You can even measure with things like your hands. It works like this. New picture, please!
This map has two locations that are labeled C and D.
Say your pinkie finger was the exact distance from point C on the map to point D.
Measuring distance with finger
Because this is a scale map, (and our scale is 1:18,000) that would mean that in real life, the distance from point C to point D would really be 18,000 of your pinkies lined up end-to-end.
When using objects to measure, the measurement must be consistent.
Another way to say this is that you would take 18,000 of this same pinkie to cross the lake and cover the distance between point C and point D.
I understand that this would be an insane amount of pinkies, but it would totally work. Now, like the king from the story, you need to keep the same measurements the whole time; you can't swap out pinkies mid project. One of your pinkies might be close in length to a friend's pinkie, but I bet they aren't the exact same. Remember, the great part about this type of map is that you can use anything as your measuring tool. Go tell your friend to find their own cool measurement!
Even if the story about the king was meant for a younger audience, can you see how these ideas are related? The king was using his foot to measure length, but the carpenter did not have the same sized shoe, so when he measured for the stable, the size was different and things got all messed up. Can you imagine trying to cram that horse into a pony-sized stable? That would be quite a trick.
Now, had the carpenter been in possession of a scale map, things would have been quite different. We could have figured out how many of the king's steps and the number of carpenter's steps would be equal. Remember, that's what a scale map does; it takes one item and tells how many of the same item would be needed in the real world to make the actual distance.
Creating a Scale Map
Let's go about making our very own scale map. Here are four simple steps you'll want to follow:
- Find a map of an area you want to use.
- Find both the actual and measured distances of two points on your map.
- Divide the actual distance by the measured distance on the map for your scale.
- Place your scale numbers on the map.
First, we need to find a map. Here, this one will do.
Creating a scale map; step 1
Step two has two parts. First, we need to find a distance that we can measure on the map itself.
Ah, these two points in the city are actually two inches apart on my map when I measured. Any two points will work, but try to find something with a nice round number if you can. Next, we need to find the actual distance between the two locations on the map, but we need to keep the units the same. Remember, that was our problem with the stable!
I looked the distance up online, and I found that these two locations are actually 800 feet apart. This is a small problem because I was using inches before, and now I have feet.
Can you help me convert 800 feet into inches? I know I need to multiply 800 by 12 because there are 12 inches in a foot. If I did my math right, that should be 9,600 inches. So now I know my two distances. On the map, A to B is two inches, and in real life, the distance is actually 9,600 inches. Onward to step three!
Next, we need to do some dividing, the actual distance divided by the map distance. Here we have 9,600 inches (the actual distance) being divided by 2 inches (the map distance). If I do 9,600 divided by 2, we end up with 4,800. Have you figured out what this actually means yet? For every inch we have on the map, it represents 4,800 inches in real life. Or another way to say this would be 1:4,800. This is our scale. Remember, this is also a ratio. This means that for every one on the map, there would be 4,800 of the same unit on the actual site.
The last step would be to actually drop this scale number onto our map. Pick a corner and make it nice and large so that it can be easily read. And there you have it. We have successfully created a scale map, and I know you'll be able to do this yourself at home. All you need now is a bit of practice. Get out there, and give it a try!
Let's review. If you look at the small mark at the bottom of a map, you will see something called a scale. The scale is actually a ratio, which means that two numbers are working together. The first number refers to the map, the second to the actual place the map represents.
Remember, this scale can be applied to any measurement, even things like your pinkie, but don't forget about the king! You need to use the same item both on the map and in the real world for this to work. Simply multiply by the number found on the map, and start counting. You could also use a ruler for this process, and convert your numbers.
When making your own scale map, remember that you need to complete four steps. First, find yourself a map. Then, using two points, find both the distance on the map and the true distance. Next, you divide the true distance by the measured map distance, and find your scale. Last, you need to place that ratio onto your map. Thanks for watching!
After this lesson, you should be able to:
- Explain what a scale map is
- Recall how to use objects other than a ruler for measurement
- Create a scale map using four steps