Geometry: Basic Ideas

Why is a Square also a Rectangle?

by Bonnie Yoder

- You know how a puppy is a kind of dog, but not all dogs are puppies? Well, the same thing
is true for lots of other categories of things, including squares and rectangles.
- Other Examples:
- All lollipops are candies, but not all candies are lollipops.
- All girls are people, but not all people are girls.
- All cars are machines, but not all machines are cars.

- Other Examples:
- Puppies, lollipops, girls and cars are all examples of specific types of a more general
category, like dogs, candy, people and machines. All the specific examples, puppies,
lollipops, girls and cars, have more characteristics that make them more specific.
- You can often make up your own special characteristics that a certain category
must have in order to be considered something more specific.
- For a dog to be a puppy it has to be a very young dog.
- For a candy to be a lollipop, it must be on a stick.

- You can often make up your own special characteristics that a certain category
must have in order to be considered something more specific.
- All of this is true of geometric shapes too! The next example is presented as a display of how a square is a special kind of rectangle.

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