Shapes On A Plane- Day 2

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SWBAT to verify experimentally the properties of rotations, reflections, and translations using transparencies.

Big Idea

After reviewing key vocabulary for the unit, students sort transformation cards into three types. Then, using a transparency and pen, they prove that at least one pair from each set is congruent to each other.

Warm Up

10 minutes

For today's Warm Up, I want students to practice applying the learning from the day before. Students must plot four different points on the coordinate grid, connect the points, and then reflect the shape across the y-axis. I then ask students to record the coordinates of the resulting points and describe what they notice. 

Once the timer sounds after 5 minutes, I select a student at random (from name sticks) and ask them to provide the coordinates for the reflected shape. I then ask the class to verify the coordinates and describe what patterns they see. I want students to begin to make sense of the patterns that emerge from each type of transformation.

Learning Objective

1 minutes

After the Warm Up, I introduce the day's Learning Objective, which is to verify experimentally the properties of rotations, reflections, and translations using transparencies. I hold up a transparency and demonstrate how they are used using the document camera.

Vocabulary Review

9 minutes

Because of the importance of academic vocabulary in this unit, I spend the next nine minutes on several Vocabulary Review activities. I select volunteers to match the key vocabulary to the formal definitions before displaying a sample of each type. Volunteers decide which of the three transformations the sample models and the class then verifies or disagrees. My goal with this quick review is to uncover any misconceptions while reinforcing the key vocabulary.

Work Time

12 minutes

For Work Time, student pairs complete the Transformation Card Sort by sorting the cards into three piles: translations, reflections, and rotations. Once they have completed sorting, I ask them to record their work in the journals in three columns that can be shared with the class during consensus building.

Next, I ask them to select one card from each pile. Then, using their transparency and pen, prove that the pair of shapes is congruent. I intentionally remain vague about these instructions as I want to see how students use what the already know about congruence to prove it with these new tools.

When the timer sounds after 12 minutes, I call the class together to build consensus.

Consensus Building

10 minutes

Once the Work Time timer sounds, I bring the class together to build consensus around their sorting task. I randomly select students to come forward to drag and drop a letter into the appropriate column on the SmartBoard based on their findings.

Typically, there is very little dissent, especially once the volunteer explains his/her thinking. Once consensus is reached for the card sort, I ask pre-selected volunteers to bring their transparency forward to the document camera to explain their work. I pre-select students with strong verbal skills to model during this part of the lesson so that weaker students can listen and decide if they agree or not without the stress of feeling like they are going to be called upon to present. By pre-selecting students, I also give them time to rehearse before coming to present before the class.


3 minutes

For closure, I take the cards from today's sort and display one for each student who must accurately name the transformation in order for them to put their journal away and leave the classroom. Instead of me telling them they are correct, I ask other students at their table to confirm. If a student miss-identifies the transformation, I show the next card so the student has the opportunity for a correct response. For stronger students, I may follow-up with "How do you know?" once they identify the transformation. This gives them an opportunity to verbalize their understanding while providing additional information for the rest of the class.