Grade 6 Mathematics · Unit 10: Math Is...Standard MPP.7

Lesson 10.210.2 Small Group · Group 1

Group 1 · Set BSecond form · new problems, same idea

Mastery check☐ Exceeds☐ Meets target☐ Needs practice
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Learning target With my small group, I can use bilateral symmetry to describe structure in nature and in human creations — one step at a time, with support.

Remember10.2 Small Group · Group 1

Bilateral symmetry means a line splits a figure into mirror halves, so matching points are the same distance from the line. A figure has bilateral symmetry when a line splits it into two halves that are mirror images.

Words: symmetric (simétrico)mirror image (imagen reflejada)bilateral symmetry (simetría bilateral)line of symmetry (eje de simetría)balance (equilibrio)

  1. 1Complete each step, then write the final answer.

    A butterfly is symmetric across the y-axis. One wing tip is at (−5, 2). The matching tip is at (?, 2). What is the missing number?

    Show your work

    Hint The tip is 5 units left of the y-axis. Count 5 units to the right.

    Final answer:
  2. 2Complete each step, then write the final answer.

    The y-axis is a line of symmetry. A point is at (−7, 3). Its mirror point is at (?, 3). What is the missing number?

    Show your work

    Hint The point is 7 units left of the y-axis. Count 7 units to the right.

    Final answer:
  3. 3Complete each step, then write the final answer.

    An architect draws a house that is symmetric across the y-axis. The left corner of the roof is at (−4, 6). The right corner is at (?, 6). What is the missing number?

    Show your work

    Hint The two roof corners are mirror points. Count the distance from the y-axis.

    Final answer:
  4. 4Complete each step, then write the final answer.

    A design is symmetric across the line x = 1, not the y-axis. One point is at (4, 2). Its mirror point is at (?, 2). What is the missing number?

    Show your work

    Hint Count how far (4, 2) is from the line x = 1. Then count the same distance past the line.

    Final answer:

Explain your thinkingHow do you find a mirror point across the y-axis? Use Lin's mistake to explain what changes and what stays the same.

Sentence starter The x-coordinate ___. · The y-coordinate stays the same because ___.

How did it go? ☐ 4 · I can teach it☐ 3 · I've got it☐ 2 · I need a hint☐ 1 · I need help