SEW - Models of Earth Lesson

 

Models of Earth

You are meeting friends at the park one afternoon but they do not know where it is. There are several ways you could get them there. You could give them verbal directions "Turn left at the stop sign, go three blocks, and turn right at the pool... " Verbal directions can be hard to follow, long, and cumbersome. Another option would be to draw a map of the best route with pictures, instead of words. The third and best option would be to give the address of the park. This way your friends could plug the address into their GPS and the GPS could use coordinates to find the exact location. Coordinates are a series of numbers used to indicate a position.

Maps are used to show the Earth's size, shape and position of surface features on a flat surface. But everyone knows the Earth is not flat, so globes are also used. A globe is a sphere model that represents the Earth's entire surface showing the relative size and shape of landmasses and bodies of water.

Maps and globes are drawn to scale and use a common set of symbols to represent the topography, the arrangement of natural and artificial physical features of an area, and other features on the Earth's surface. Map makers will use symbols to represent certain features for mountains, oceans, etc. If there are symbols on a map, then a key must be provided to explain what the symbols mean. Maps will also use a compass rose or north arrow to indicate direction.

Most maps and globes show grid lines, which act as a reference system to help keep track of where things are. The grid system is based on two imaginary lines: the equator and the prime meridian. The equator is an imaginary line half way between the North and South poles that divides the Earth into Northern and Southern Hemispheres. The prime meridian is another imaginary line, passing through Greenwich, England, which divides the earth into the Eastern and Western hemispheres.

 

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