This is a card-sort for triangles, rectangles, squares, and circles. There is a title card and defining attributes for each shape, as well as 4 picture cards of each shape. This set comes in black and white, and also in color. You can choose to print the set of pages that fits your needs.
Suggested Lesson: Provide students with the name and shape cards. Have students sort the shapes under the appropriate headings. Then get them to discuss what they notice about each shape, what attributes or features do they have in common? (closed, round, three-sided, etc.) Then pass out the attributes and have students place the observed attributes with the correct shapes. This will reassure the students observations, create conversation about unknown attributes, and get the kids working collaboratively while using mathematical language.
In the end, discuss non-defining attributes such as color, size, and orientation. For example, if a shape is defined as a circle, it is a circle whether it is big or small, green or purple, and so on.