Why can two maps of my town look so different?

Picture the big map on a board by the park gate, its colors pale from the sun. Now think of the bus map at the bus stop, with its bright, wiggly lines. Both of them show your town, yet they hardly look alike.

One map is full of green patches and winding paths. The other is mostly colored lines and dots. So why can two maps of the very same town look so different? Let's find out together.

A map is a drawing of a place the way a bird would see it from high above. Your whole town has to fit on one sheet of paper, so the drawing is much smaller than the town. On that sheet there is no room for every tree, car and doorbell.

That is why each map has a mapmaker who chooses what goes in and what stays out. Before drawing, the mapmaker asks one question: what is this map for? Whatever helps with that job goes on the paper, and the mapmaker leaves the rest out.

The mapmaker of the bus map wants riders to find their bus. So she draws each bus route as a bright line and each stop as a dot. She leaves out the playgrounds and ponds, because a rider does not need them.

The mapmaker of the park map has a different job: helping families find their way on foot. He draws the walking paths, the pond, the playground and the toilets. He leaves out the bus lines, because walkers do not need them. Same town, different job, so the maps look different.

A mapmaker makes one more choice: the scale, which means how much smaller the map is than the real place. Someone drawing only your street can pick a close-up scale. Then each house, each driveway and even the swings fit on the page. So which things do you think stay on the map when a mapmaker squeezes the whole town onto that same page?

With a faraway scale, each house would shrink smaller than a crumb. So the mapmaker leaves the houses out and keeps only the big roads, the river and the parks. The town turns into a few lines and patches, and it looks nothing like the close-up map.

Two maps of your town look different because each mapmaker draws for a different job and picks only what helps with that job. Each mapmaker also chooses a scale, close up or far away, and that changes how much fits on the page.

The bus map and the park map lie side by side. One is full of bright lines, the other full of paths and ponds, and the same blue river curls through both.