standard_description: Use coordinates to prove simple geometric theorems algebraically. For example, prove or disprove that a figure defined by four given points in the coordinate plane is a rectangle; prove or disprove that the point (1, Ö3) lies on the circle centered at the origin and containing the point (0, 2).
problem_activity: Task
As a whole group, students will sort a collection of three-dimensional objects into categories by shape. There should be several that fall into each of the categories below:
sphere
cone
pyramid
cube
cylinder
rectangular prism
As a class, students brainstorm attributes of the objects they have classified, and the teacher writes those attributes where the entire class can see them. Students then use one of the following sentence frames as they classify the objects. The sentence frames should be written on sentence strips or some other large paper so that the entire class can read/see them during the activity.)
The ___________ is in the shape of a __________ . It is/has __________ , just like all ____________.
The ___________ is in the shape of a __________ . It is/has ___________ , but some ___________ aren't/don't.
The teacher models with one or two objects to start. An example would be:
"The can is in the shape of a cylinder. It has circles on the ends, just like all cylinders."
"The can is a in the shape of a cylinder. It is made of metal, but some cylinders aren't."
This will help students distinguish between defining attributes and non-defining attributes.
Once students are familiar with this task they can be given a set of cards and can work in pairs to classify by defining attribute using the (now familiar) sentence frames.


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