- Second Grade
- 40 minutes
- Standards: 2.G.1
Shape up your students' understanding of geometrical attributes with this hands-on math lesson. Students will gain a better understanding of how to describe a shape by the number of edges and vertices it has, rather than by its name.
Students will be able to name shapes according to the number of edges and vertices.
Introduction (3 minutes)
- Display a triangle to the class, either by drawing it on the whiteboard or using an interactive whiteboard. Ask your students to call out the name of the shape.
- Discuss the shape attributes as a class. Great discussion questions include: How many sides does a triangle have? Are they straight or curved? How many corners does a triangle have?
- Point to each corner on the triangle. Explain to the class that a vertex is the place where two sides meet in a corner. Tell the class that a triangle has three vertices, the plural word for vertex.
- Count the sides of the triangle together. Explain that each side is a line that connects two vertices, also known as an edge.
- Announce to the class that today they will learn how to describe the attributes of a shape to describe it, instead of always just using its name.
Explicit Instruction/Teacher Modeling (7 minutes)
- Draw and label a rectangle and pentagon on the board.
- Explain that shapes are made up of a set of sides or curved segments. Straight sides are the edges of each shape.
- Draw a circle on the whiteboard. Ask the class how many edges a circle has.
- After some discussion, tell the class that a circle doesn't have any edges or vertices, since there aren't any straight lines or corners on a circle.
- Point to the rectangle and demonstrate how to count the edges and vertices. Explain to students how the number of edges and the number of vertices are the same.
- Point to the pentagon and count the number of edges and vertices.
Guided Practice/Interactive Modeling (10 minutes)
- Give each student the following pattern blocks: triangle, trapezoid, hexagon, and square.
- Ask students to hold up the correct pattern block as you call out the number of edges or vertices a shape has. As you call out numbers, remind students that the number of edges and vertices a shape has is the same.
- Answer any questions your students have about this concept.
Independent Working Time (10 minutes)
- Pass out a copy of the 2-Dimensional Shapes worksheet to each student.
- Have students complete the sheet on their own.
- Enrichment: Challenge advanced students to draw and label more advanced shapes, such as hexagons, heptagons, octagons, and decagons. Instruct them write a riddle for each shape name on a sheet of paper, which includes the correct number of edges and vertices the shape has.
- Support: Encourage struggling students to use pattern blocks to trace the triangle, hexagon, and trapezoid. Ask them to count the number of sides and to write the number beside the drawing.
Related Books and/or Media
Assessment (5 minutes)
- Pass out a sheet of drawing paper to each student. Instruct your students to draw and label a pentagon on the paper.
- Remind students that they should count and label the edges and vertices on the paper as well.
Review and Closing (5 minutes)
- Ask students to look around the classroom and name objects with three, four, or five edges.
- Make a list of all the objects.