Mathematics Advanced Year 11 - Module 1 - Lesson 10
Reflections of Functions
1. Key Ideas
When a video game character turns around, the artist does not redraw the entire sprite — they simply flip the image horizontally. In mathematics, we can flip graphs too: across the $x$-axis, across the $y$-axis, or both. These reflections are powerful tools for sketching and understanding symmetry.
- $-f(x)$ reflects the graph in the $x$-axis
- How reflections affect the coordinates of key points
2. Success Criteria
By the end, you should be able to:
- $-f(x)$ reflects the graph in the $x$-axis
- $f(-x)$ reflects the graph in the $y$-axis
- $-f(-x)$ reflects in both axes
3. Key Terms
4. Activity: Build the Lesson Map
Use the lesson to complete the table. Keep answers brief but specific.
| Prompt | Your answer |
|---|---|
| Main concept | |
| Important example | |
| Common mistake to avoid | |
| How this links to the next lesson |
5. Short Answer Questions
1. Explain this lesson goal in your own words: "$-f(x)$ reflects the graph in the $x$-axis". Use one specific example from the lesson.
2. Apply this idea to a new example: "$f(-x)$ reflects the graph in the $y$-axis". Show your reasoning clearly.
3. Analyse why this idea matters for understanding Reflections of Functions: "$-f(-x)$ reflects in both axes".
6. Extend: Apply the Idea
A student gives a memorised answer about Reflections of Functions but does not use evidence or reasoning.
Improve the answer by writing a stronger response that uses accurate terminology, a relevant example and a clear explanation.
7. Multiple Choice
1. What is the best first step when answering a question about Reflections of Functions?
A. Identify the key concept being tested
B. Write every fact from memory
C. Ignore the command word
D. Skip examples and evidence
2. Which answer would show stronger understanding of Reflections of Functions?
A. An answer with accurate terms and reasoning
B. A copied definition only
C. A single-word response
D. An answer with no example
3. What should you do if a question asks you to explain?
A. Link the idea to a reason or cause
B. List unrelated facts
C. Only draw a diagram
D. Write the shortest possible answer
8. Success Criteria Proof
Finish with evidence that you can do each success criterion.