To begin, I want to review different forms of equations. As a result of the most recent assessment, I realize that students are still struggling with equations with a start unknown or a change unknown (such as 8 + ___ = 23).
I present the students with the problem 9 + ___ = 25. I write it on the board and put a magnifying glass symbol in the blank space. I remind the students that in the past we have been detectives looking for the mystery number and that today we will try that again. I ask students to write the equation in their math journals and to solve the problem. We share answers and solutions. Students could use different strategies to either add on to 9 or subtract 9 from 25.
I write another problem, 24 - ___ = 10. (Again I put the magnifying glass in the blank.) Students solve the problem and then we share answers and solutions. Students might use different strategies to count down from 24 to 10, count up from 10 to 24, or subtract 10 from 24.
I continue the process with the following problems:
___ + 18 = 26
___ - 8 = 20
7 + ___ = 30
73 - ___ = 53
If students struggle with these, I can continue with additional problems. If students are confident in finding the mystery number, I will move on to today’s lesson.
Today students will work with the attributes of shapes. Common Core Standard 2.G.A.1 says that students should be able to recognize and draw shapes having specified attributes, such as a given number of angles or a given number of equal faces.
I begin by reviewing the terms vertex or vertices (where 2 line segments meet), face (flat side of a 3D figure), edge (connecting two vertices), angle (the opening inside the vertex or corner). I review these terms by holding up different shapes and pointing to the corners, edges, etc.
Next I ask for volunteers to show me an angle, edge, face, and vertex.
I hand each student a 6 inch straightedge and a piece of drawing paper. I ask them to fold the paper in half on its line of symmetry. I ask them to fold the paper again on a different line of symmetry. They should now have 4 even sections on their paper. I ask students to number the 4 sections 1,2,3,4.
I tell students that I will describe a shape to make but they will have to follow my clues and listen carefully. I want them to attend to the precision of my descriptions as they make their shapes. (MP6)
“In box number 1 I want you to draw a shape that has 4 sides. Two of the sides are parallel to each other, the other two sides are parallel to each other but not to the first 2 sides. There are 4 square angles and 4 edges to the shape. Only 2 lines can be the same length. The other 2 must be a different length from the first two but should be the same as each other." (rectangle)
“In box number 2 the shape will have 3 edges and 3 vertices. The lines do not have to be the same length.” (triangle)
“In box number 3 the shape should have 6 angles and 6 edges. Each edge should be the same length.” (hexagon)
“In box number 4 the shape will have 4 sides. None of the sides can be parallel. There are 4 vertices and 4 angles. None of the angles are square angles. “ (kite)
“Now for fun turn your paper over and try to draw a shape that has no angles, no straight edges, and no vertices.” (circle)
Once all the shapes are drawn I ask students to show their drawings to their table mates. Did they agree on what shape was in each box? What differences did they find?
Now we review the shape descriptions together. We clear up any confusions about which shape is which.
I tell students that today they describe the attributes of certain pattern blocks. They will work in partners. The first person will close his/her eyes while the second person selects a block and looks at it and then hides it in his/her hands. The person with the block will give clues such as the block has 4 corners, the block has 3 sides, etc. Their partner should try to guess what block their partner is describing. After 3 guesses the person shows the block (if their partner has not yet guessed it) and they switch roles.
To give students further practice with shapes and their attributes, students are given templates that have squares, circles, triangles, hexagons, trapezoids and rhombuses on it. First we play an "I'm thinking of game" that asks students to attend with precision to what I say (MP6). I say, "I am thinking of a shape that has exactly 4 sides. only 2 of the sides are parallel. The other 2 sides are not parallel. I am thinking of the larger one of these shapes, can you point to it?" Students should point to the large trapezoid.
After practice with 6 different sets of clues, I tell students that they can make a picture using the templates but they must use exactly 3 of each shape. The picture should be a picture and not just a drawing of the shapes. I want students to continue to look at the different shapes and the attributes of each one.