Altersgruppe: Grade 2 Virginia - Mathematics Standards of Learning (2009): 1.12, 1.16, Virginia - Mathematics Standards of Learning (2016): 3.12.

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1 1 U n t er r ich t splan Classify Polygons Based on Vertices, Ed ges and Angles Altersgruppe: Grade 2 Virginia - Mathematics Standards of Learning (2009): 1.12, 1.16, 2.16, 3.14, 4.12a, 4.12b Virginia - Mathematics Standards of Learning (2016): 3.12.a, 3.12.b, 3.12.c Fairfax County Public Schools Program of Studies: 1.12.a.5, 1.12.a.6, 1.16.a.1, 2.16.a.1, 2.16.a.2, 2.16.a.3, 2.16.a.4, 2.16.a.5, 3.14.a.2, 4.12.a.1, 4.12.a.2, 4.12.b.1 Online-Ressourcen: P o l ygo l f Opening Teacher present s Students pract ice Closing 1 5 min 5 min 20 min 5 min M at h Obj ect ives P rac t i c e identifying geometric shapes Learn the concepts vertices, sides (edges), and angles De vel o p an acquaintance with polygons with different attributes and when displayed in different orientations

2 2 Ope ni ng 15 min Draw on the board a straight line. Example: Say: What is this? This is a straight line. Say: What are the attributes of a straight line? A straight line does not have an end. It continues all the way left and right. The arrow at the left and right of the line express that fact. Draw on the board a ray. Example: Say: What is this? This is a ray. Say: What are the attributes of a ray? Ray is a part of a line. It has an endpoint and continues infinitely in one direction. Draw on the board a line segment. Example: or

3 3 Say: What is this? This is a line segment. Say: What are the attributes of a line segment? A line segment is a part of a line that is bounded by two distinct end points. That is the reason why we can measure the length of the line segment. Draw on the board 2 rays connected in one point. Example: Say: What is this? An angle. Say: What are the attributes of an angle? It is made up of two rays that meet an a vertex. Show how we identify the angle we measure. Example:

4 4 Say: An angle is the figure formed by two rays, called the sides of the angle, sharing a common endpoint, called the vertex of the angle. Actually when we draw the rays we defined 2 angles, so we draw an arc to define the angle we are talking about. Point at the arc that mark the angle and at the sides of the angle. Say: The angle is the amount of turn between two straight lines that have a common endpoint (the vertex). Say: If we want to draw a polygon, we define it by line segments which we call edges. We can draw shapes without line segments, but then it will not be a polygon. Ask: What do we call a polygon with 3 sides?? A triangle. Draw a triangle on the board. Write the number 3 inside the triangle. Example: Ask: How many vertices does the triangle have? A triangle has 3 vertices. Ask: How many angles the triangle has?

5 5 A triangle has 3 angles. Label the vertices, sides (or edges) and angles. Example: Draw a quadrilateral on the board. Ask: What names can we give this shape?? Depending on the shape, students may say polygon, quadrilateral, etc. Ask: How many vertices the quadrilateral has? Quadrilateral has 4 vertices. Ask: How many angles the quadrilateral has? Quadrilateral has 4 angles. Write the number 4 inside the Quadrilateral. Label the edges, vertices and angles of the quadrilateral on the board. Continue with other sample polygons. Ask: Is there a connection between the number of vertices, sides (or edges) and angles in a polygon? Yes. in a polygon, the number of vertices, sides and angles are equal.

6 6 T e ac he r prese nt s mat h game : P o l ygo l f - Cl assi f y P o l ygo ns: Level I 5 min Present Matific s episode Po ly Go lf - C la s s if y Po ly go ns : L e v e l I to the class, on the projector. This episode practices the classification of polygons based on the number of vertices, sides, and angles. A stack of polygons is on top of a golf hole. Every time you click a polygon with a specified property, the polygon disappears and the golf ball gets nearer to the hole. Note: This episode does not have a preset mode, so the tasks in this episode may vary from the directions that follow. Example : Say: Please read the instructions at the bottom of the screen. (The task may be different each time the episode is played). Students can read the instructions. Ask: Which shape has those attributes? Students answers may vary.

7 7 Ask: What name can we give that shape? Students responses vary. Click on the shape with those attributes to make it disappear. Example : Continue to play the episode, asking students about the attributes and names of the shapes. St ude nt s prac t i c e mat h game : P o l ygo l f - Cl assi f y P o l ygo ns: Level I 20 min Say: Now it s your turn to play match the shapes with the attributes. Have students play Po ly Go lf - C la s s if y Po ly go ns : L e v e l I and Po ly Go lf - C la s s if y Po ly go ns : L e v e l I I on their personal devices. Circulate, answering questions as necessary.

8 8 Cl o si ng 5 min Ask the following questions for discussion with the whole class, small groups, partners, or as an individual reflection. What is the difference between a line, a ray, and a line segment? What is the relationship between a shape s sides, angles, and vertices? Draw or display an example of a shape. What is this shape s name? What are its attributes? Opt io nal Ext e ns io n dis c us s io n Say: What happens when I draw two lines in a plane? Draw samples on the board. Discuss the attributes of intersecting and parallel lines. Say: Straight lines can also not intersect at all. Those lines called parallel lines, and the distance between those lines stays the same wherever we check. Draw a pair of parallel straight lines on the board. Example:

9 9 Say: Parallel lines will not intersect at all. We learned that rays that sharing a common endpoint define a vertex and an angle, so that the measure of the angle is the magnitude of the smallest rotation that maps one of the rays into the other. In a parallel lines situation, there is no such magnitude and that is the reason why there cannot be a vertex and an angle between those lines. Demonstrate, using a long stick (a broom or a long ruler) how a rotation of one of the lines cannot map the ray into the other. Only translation of one of the lines can map one line into the other.