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Geometry Session 10, Grades K-2: solutions
Session 10 Session 10 K-2 Part A Part B Part C Homework
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Session 10 Materials:



Solutions for Session 10, Part B

See solutions for Problems: B1 | B2 | B3 | B4 | B5

Problem B1

Answers will vary. Some possible responses:


(Level 0 thinking) The students' natural response was to name the particular shape they were holding rather than to focus on properties. Also, they relate the shapes to others they know, thinking of a trapezoid as half a hexagon.


(Level 1 thinking) The activity forces students to feel a shape, turning it around in their hands, and learn that it is the same shape no matter what its position or orientation. They are trying to focus on properties and how they can determine the class of shape from those properties.

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Problem B2

Answers will vary. Some examples of level 1 thinking required by the activity include the identification of non-standard kinds of polygons (concave, asymmetric, etc.). Also, level 1 thinking requires knowing if you've already counted one of the shapes, even if you find it a different way or list the vertices in a different order.

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Problem B3

Answers will vary. Some possible answers:


Key pieces of geometry are names, properties (number of sides and vertices), and naming of polygons. In addition, you need to be flexible in your thinking about polygons, recognizing irregular and concave polygons in addition to more regular and familiar ones.


Reasoning includes algorithmically finding every polygon, determining if you have found duplicates, and determining when you are done.

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Problem B4

Answers will vary. Students will probably get a broader view of polygons, including familiarity with irregular and differently oriented polygons. They may struggle with the naming of polygons and with finding all of them in the more complicated figures.

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Problem B5

Answers will vary. Some ideas: Alter the activity to have less of a focus on the naming of vertices; include opportunities to draw, color, or cut out the shapes. If students have seen lots of examples of irregular polygons and have had opportunities to cut up and put polygons together to form others, they will have more success with an activity like hidden polygons.

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