1. Lesson Topic: Symmetry in the Coordinate Plane
Lesson Objective: I can…
Locate reflections of coordinate points across both axes on the coordinate plane using the x-axis and/or y-axis as the line of symmetry.
1:47
Friday
It’s important in the real world: finding and comparing locations with more than 2 directions
Remind students of behavior goal

2. Preview of Exit Ticket
1. Start at (-5, 2). Reflect across the x-axis. What point do you end up at? 2. Start at (-5, 2). Reflect across the y-axis. What point do you end up at? Challenge: Come up with a starting point and a set of directions to navigate to an ending point, including at least one reflection. Be sure to include what the ending point is.
1:48

3. Opening Exercise
Give an example of two opposite numbers and describe where the numbers lie on the number line. How are opposite numbers similar and how are they different?
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4. 1:55
When you’re done,
Compare with table

5. 2:00
How do you know?
What strategies did we use?
Compare with table

6. Exercise, continued…
When the coordinates of two points are (𝑥, 𝑦) and (−𝑥, 𝑦), what line of symmetry do the points share? Explain.
When the coordinates of two points are (𝑥, 𝑦) and (𝑥,−𝑦), what line of symmetry do the points share? Explain.
2:02
When you’re done,
Compare with table

7. Let’s Sum it Up… Answer the following questions in complete sentences:
What does a reflection of a point across a line of symmetry on the coordinate plane look like?
How do we find the ordered pair of a point reflected across an axis?
Why is this important to know how to do?
2:04
(what are the steps for this process)

8. Example 2: Navigating the Coordinate Plane using Reflections
Where are you after you follow the directions?
Begin at (7, 2). Move 3 units down, then reflect over the y-axis.
Begin at (4, -5). Reflect over the x-axis, then move 7 units down, then to the right 2 units.
Begin at (-3, 0). Reflect over the x-axis then move 6 units to the right. Move up two units, then reflect over the x-axis again.
Begin at (-2, 8). Decrease the y-coordinate by 6. Reflect over the y-axis, then move down 3 units.
Begin at (5, -1). Reflect over the x-axis, then reflect over the y-axis.
*Come up with your own starting points and directions.
2:08
Compare with table

9. Example 3: Describing How to Navigate the Coordinate Plane
Describe a sequence of directions to navigate from the starting point to the ending point.
Begin at (9, -3) and end at (-4, -3). Use exactly one reflection across an axis.
Begin at (0, 0) and end at (5, -1). Use exactly one reflection across an axis.
Begin at (0, 0) and end at (-1, -6). Use exactly two reflections across axes.
*Find other sequences that would work for each set of points above.
2:12
Compare with table

10. Lesson Summary
When the coordinates of two points differ only by one sign, such as (-8, 2) and (8, 2), what do the similarities and differences in the coordinates tell us about their relative locations on the plane?
What is the relationship between (5, 1) and (5, -1)? Given one point, how can you locate the other?
2:15
opposites
“Why is this important to know how to do? / Can anyone think of an example in which it would be important?”: finding and comparing location with more than 2 directions

11. Evaluate Your Learning
How will you “Sharpen Your Saw”?
2:17

12. Exit Ticket (on Socrative)
1. Start at (-5, 2). Reflect across the x-axis. What point do you end up at?
2. Start at (-5, 2). Reflect across the y-axis. What point do you end up at?
Challenge: Come up with a starting point and a set of directions to navigate to an ending point, including at least one reflection. Be sure to include what the ending point is.
*When you’re done, close your iPad and get a homework worksheet.
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