Proportionality Relationships
I.SectionObjectives
- Identify proportional segments when two sides of a triangle are cut by a segment parallel to the third side.
- Divide a segment into any given number of congruent parts.
II.ProblemSolvingActivity-MidsegmentMatch-up
- To prepare this activity, you will need to draw a bunch of triangles and cut them along the midsegment line.
- Then pass out one part of a triangle to each student.
- Students need to measure their part of the triangle.
- Then, they need to find the student who has their match.
- Students walk around the room and find a match for their triangle.
- When finished, all of the triangles should be complete.
- Once students have found a match, or think that they have, they need to write proportions to justify their
thinking. - Allow time for the students to share their work when finished.
III.MeetingObjectives
- Students will identify proportional segments when two sides of a triangle are cut by a segment parallel to the
third side.
IV.NotesonAssessment
- Observe students as they walk around finding the match for their triangle part.
- Notice if students are using measurements or not.
- If not, remind students to look for the proportionality in the measurements of each section of the triangle.
- Be sure to listen as students share their work.
- Are they able to articulate why the triangles are similar?
- Is the match that they selected an accurate match?
- Offer feedback/correction as needed.
Similarity Transformations
I.SectionObjectives
- Draw a dilation of a given figure.
- Plot the image of a point when given the center of dilation and scale factor.
- Recognize the significance of the scale factor of a dilation.
II.ProblemSolvingActivity-T-ShirtDilation
- Use the picture of Mickey Mouse for this problem- Figure 07.07.01
- http://en.wikipedia.org/wiki/Mickey_mouse
- Provide students with a copy of the picture.
- Then have students measure the height of Mickey Mouse according to the picture.
Chapter 5. Geometry TE - Problem Solving