Caught in a Net. SETTING THE STAGE Examine and define faces of solids. LESSON OVERVIEW. Examine and define edges of solids.

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1 Caught in a Net LESSON FOCUS Using informal geometric vocabulary to describe physical objects and geometric figures. Constructing mental and physical images of common geometric figures. Classifying geometric figures: triangles, circles, squares, cubes, and spheres. COMPANION ANCHORS LESSON Faces MATERIALS Excursions student page 79 Transparency TR1 Home Connection page 80 Three-dimensional models: cube, sphere, cone, cylinder, square pyramid, triangular pyramid, and rectangular prism Cardboard box cut open as a net Yarn, pre cut 4-foot and 6-foot lengths (eight 4-foot lengths and four 6-foot pieces for each group of 4 children) Clay balls or gumdrops (17 for each child) and toothpicks (26 for each child) Bendable straws and string or twist ties cone cube cylinder edge face net net frame LANGUAGE DEVELOPMENT pyramid rectangular prism space frame sphere three-dimensional figure vertex, vertices SETTING THE STAGE Examine and define faces of solids. Hand out a set of three-dimensional models to each group. Explain that a face is a flat surface of a solid figure. Show the class a cube and ask them to examine the cube at their table. Ask, What shape are the faces on a cube? (All cube faces are square.) Do the same with the cone, cylinder, sphere, pyramids, and rectangular prism (cone has one circular face, cylinder has two circular faces, sphere has no faces, square-based pyramid has one square face and four triangular faces, triangularbased pyramid has four triangular faces, and rectangular prism has six rectangular faces). Examine and define edges of solids. Explain that an edge is where the sides of two faces meet on a solid figure. Model the counting of edges on the various space figures. Examine and define vertices of solids. Explain that a vertex on a solid figure is a corner or a point where edges meet. Tell them that the term for more than one vertex is vertices. Model the counting of vertices on the various solid figures. LESSON OVERVIEW In this lesson, children identify attributes of threedimensional figures. Space frames for a cube and a rectangular prism are made of four children and eight pieces of yarn. Children use gumdrops and toothpicks as vertices and edges for space figures. Children construct space frames of figures from nets (net frames) made by connecting straw outlines of the faces. Children open boxes at home to find their nets. 60

2 UNIT B Caught in a Net BUILDING CONCEPTUAL KNOWLEDGE Groups create a cube with yarn and four children. Have children work in groups of four. Make sure children in each group are of similar height (ideally 4 feet with arms raised). Give each group four 4-foot lengths of yarn. Ask children to build a square on the floor with their pieces of yarn. Remind children that a vertex is where two sides on a plane figure or two or more edges on a space figure meet. Instruct each child in the group to step on one vertex of the square so that all vertices are covered. Give each group four more 4-foot sections of yarn. Ask each child in the group to hold one piece of yarn. One child will hold one end of his or her yarn piece and give the other end to a child standing on an adjacent vertex. That child will hold one end of his or her yarn piece with the piece he or she was just given and give the other end to the next child in the square. Continue until each child is holding the ends of two different pieces of yarn. School District of Hillsborough County. Copying this page without written permission of Metropolitan Teaching and Learning Company is illegal. Name Caught in a Net EDGES AND VERTICES 5Create a square-based pyramid and a cube using gumdrops for the vertices and toothpicks for the edges. Count the edges (toothpicks) and vertices (gumdrops) on each shape. Record your results. Shape UNIT B Caught in a Net Edges Vertices 8 5 Square-Based Pyramid Cube 12 8 seventy-nine 79 Ask children to stand as straight as possible and to raise both hands straight above their heads while holding onto the pieces of yarn. Tell children that each person and each piece of yarn represents one edge of a three-dimensional figure called a cube. Ask children to count the edges on their cube. Once again, remind children that a vertex on a solid figure is where two or more edges meet. Ask children how many vertices they are standing on. Ask children how many vertices they are holding in the air. Ask them whether there are any other vertices. Then ask, How many vertices does a cube have (8)? Groups create a rectangular prism with yarn and four children. Exchange four 6-foot lengths of yarn for two opposite edges on the top and two opposite edges on the bottom of the cube to create a rectangular prism. Ask children to compare the cube and rectangular prism. Encourage children to compare number of edges, number of vertices, and lengths of edges. BUILDING SKILLS AND STRATEGIES Children construct space frames of threedimensional figures. For this activity, each child will need 17 gumdrops and 26 toothpicks. You may substitute balls of modeling clay for the gumdrops. Have children turn to Edges and Vertices, page 79, in their books. Read the directions aloud. Circulate as children complete the activity. FOCUS ON LANGUAGE Explain to children that a net is a flat pattern or plan of the surfaces of a three-dimensional figure. A net for a rectangular prism is like a cardboard box that has been opened up. Page 79 61

3 UNIT B Caught in a Net PUTTING IT INTO ACTION Create a rectangular prism with a cardboard box net. Display the net made from the opened box. Fold the faces together to form its original rectangular prism. Have children identify the faces, the edges, and the vertices. Use a marker to draw the outlines of the faces. Make three-dimensional figures with net frames made of straws. Pass out several bendable straws to each group. Demonstrate how to hook two straws together. Bend one straw. Squeeze the short end of the straw and bend the squeezed part in half. Push the squeezed end of the straw into the large end of a second straw until only the bendable piece and long section of the first straw are showing. Add another straw. Add a fourth straw. Connect both ends to the three-straw figure to complete a square. Tell children you have just made the outline of a face. Next, demonstrate how to build a rectangle by inserting one additional straw in two of the opposite sides. Then demonstrate how to build a triangle using only three straws. Instruct each table to construct seven squares and eight triangles. Finally, demonstrate how to connect pieces together by tying string or using twist ties to make the outline of nets or net frames. Children make three-dimensional figures with net frames made of straws. Display transparency Caught in a Net, TR1. Instruct half the groups to construct the net frames on the left side of the overhead transparency and the other groups to construct the net frames on the right side of the transparency. Tell children to bring the net frames together and connect them to form a three-dimensional figure. Name each solid figure. Ask children to count the edges and vertices. EXTENSION Children investigate different net frames for the same figures. Challenge the groups to make a net frame for a cube, triangular pyramid, or square-based pyramid that is not shown on the overhead transparency. Check the nets by bringing them together. Make sure you show examples that work and examples that don t work! Build a net frame for a rectangular prism. Cut off two inches from the long end of two straws. Using two full straws and the two cut straws, make rectangles. Build a net frame of a rectangular prism. HOME CONNECTION Connect Have children take home and complete Home Connection, page

4 Name Caught in a Net EDGES AND VERTICES 5Create a square-based pyramid and a cube using gumdrops for the vertices and toothpicks for the edges. Count the edges (toothpicks) and vertices (gumdrops) on each shape. Record your results. School District of Hillsborough County. Copying this page without written permission of Metropolitan Teaching and Learning Company is illegal. Shape UNIT B Caught in a Net Edges Vertices Square-Based Pyramid 8 5 Cube 12 8 seventy-nine 79

5 HOME CONNECTION: NETS Dear Parent or Guardian: Your child has been learning about nets. A net is a flat pattern for the surface of a three-dimensional figure. Help your child find and open up boxes (cereal, cracker, etc.) to see their nets. Example Two Possible Nets 80 eighty UNIT B Caught in a Net

6 Unit B Caught in a Net TR1