What Is the Same?
5 min
Teacher Prep
Setup
Narrative
In this activity, students consider shapes which are mirror images of each other. They identify which have the same orientation by selecting the figures which represent a right hand. Then, students discuss what is the same and what is different about the figures, identifying specific features that are the same among all of the figures.
Providing access to tracing paper, rulers, and protractors in the geometry toolkit allows students the opportunity to choose appropriate tools strategically (MP5).
Launch
Arrange students in groups of 2, and provide access to geometry toolkits. Give 2 minutes of quiet work time, followed by time for sharing with a partner and a whole-class discussion.
Show students this image or hold up both hands and point out that our hands are mirror images of each other. These are hands shown from the back. If needed, clarify for students that all of the hands in the task are shown from the back.
Student Task
A person’s hands are mirror images of each other. In the diagram, a left hand is labeled. Shade all of the right hands.
Sample Response
Activity Synthesis (Teacher Notes)
Ask students to think about the ways in which the left and right hands are the same, and the ways in which they are different.
Some ways that they are the same include:
- The side lengths and angles on the left and right hands match up with one another.
- If a left hand is flipped, it can match it up perfectly with a right hand (and vice versa).
Some ways that they are different include:
- They can not be lined up with one another without flipping one of the hands over.
- It is not possible to make a physical left and right hand line up with one another, except as “mirror images.”
Math Community
After the Warm-up, display the revisions to the class Math Community Chart that were made from student suggestions in an earlier exercise. Tell students that over the next few exercises, this chart will help the class decide on community norms—how they as a class hope to work and interact together over the year. To get ready for making those decisions, students are invited at the end of today’s lesson to share which “Doing Math” action on the chart is most important to them personally.
Standards
- 8.G.1·Verify experimentally the properties of rotations, reflections, and translations:
- 8.G.A.1·Verify experimentally the properties of rotations, reflections, and translations:
- 8.G.2·Understand that a two-dimensional figure is congruent to another if the second can be obtained from the first by a sequence of rotations, reflections, and translations; given two congruent figures, describe a sequence that exhibits the congruence between them.
- 8.G.A.2·Understand that a two-dimensional figure is congruent to another if the second can be obtained from the first by a sequence of rotations, reflections, and translations; given two congruent figures, describe a sequence that exhibits the congruence between them.
15 min
10 min
Knowledge Components
All skills for this lesson
No KCs tagged for this lesson
What Is the Same?
5 min
Teacher Prep
Setup
Narrative
In this activity, students consider shapes which are mirror images of each other. They identify which have the same orientation by selecting the figures which represent a right hand. Then, students discuss what is the same and what is different about the figures, identifying specific features that are the same among all of the figures.
Providing access to tracing paper, rulers, and protractors in the geometry toolkit allows students the opportunity to choose appropriate tools strategically (MP5).
Launch
Arrange students in groups of 2, and provide access to geometry toolkits. Give 2 minutes of quiet work time, followed by time for sharing with a partner and a whole-class discussion.
Show students this image or hold up both hands and point out that our hands are mirror images of each other. These are hands shown from the back. If needed, clarify for students that all of the hands in the task are shown from the back.
Student Task
A person’s hands are mirror images of each other. In the diagram, a left hand is labeled. Shade all of the right hands.
Sample Response
Activity Synthesis (Teacher Notes)
Ask students to think about the ways in which the left and right hands are the same, and the ways in which they are different.
Some ways that they are the same include:
- The side lengths and angles on the left and right hands match up with one another.
- If a left hand is flipped, it can match it up perfectly with a right hand (and vice versa).
Some ways that they are different include:
- They can not be lined up with one another without flipping one of the hands over.
- It is not possible to make a physical left and right hand line up with one another, except as “mirror images.”
Math Community
After the Warm-up, display the revisions to the class Math Community Chart that were made from student suggestions in an earlier exercise. Tell students that over the next few exercises, this chart will help the class decide on community norms—how they as a class hope to work and interact together over the year. To get ready for making those decisions, students are invited at the end of today’s lesson to share which “Doing Math” action on the chart is most important to them personally.
Standards
- 8.G.1·Verify experimentally the properties of rotations, reflections, and translations:
- 8.G.A.1·Verify experimentally the properties of rotations, reflections, and translations:
- 8.G.2·Understand that a two-dimensional figure is congruent to another if the second can be obtained from the first by a sequence of rotations, reflections, and translations; given two congruent figures, describe a sequence that exhibits the congruence between them.
- 8.G.A.2·Understand that a two-dimensional figure is congruent to another if the second can be obtained from the first by a sequence of rotations, reflections, and translations; given two congruent figures, describe a sequence that exhibits the congruence between them.