Spherical Mirrors: Concave and Convex

Active learning works for spherical mirrors because students need to see, touch, and sketch how curved surfaces bend light. When they hold mirrors and trace rays themselves, the abstract rules about focal points and image types become clear.

• Class 7
• Science (EVS K-5)
• 4 activities
• 20 min–45 min

Learning Objectives

1. Compare the nature and characteristics of images formed by concave and convex mirrors at different object positions.
2. Explain the scientific principles behind the use of concave mirrors in shaving mirrors and vehicle headlights.
3. Analyze why convex mirrors are preferred for rearview applications in vehicles, considering their field of view.
4. Differentiate between real and virtual images formed by spherical mirrors.
5. Demonstrate the formation of images using ray diagrams for both concave and convex mirrors.

Stations Rotation

⏱ 45 min·Small Groups

Stations Rotation: Mirror Observation Stations

Prepare three stations with concave mirror, convex mirror, and ray box. Place objects at focus, between pole and focus, and beyond centre of curvature. Groups observe images, note position, size, nature, and sketch ray diagrams. Rotate every 10 minutes and compare findings.

Prepare & details

Differentiate between the types of images formed by concave and convex mirrors.

Facilitation Tip: During the Mirror Observation Stations, place a lamp or torch behind each mirror so students can see the reflected light patterns clearly.

Setup: Designate four to six fixed zones within the existing classroom layout — no furniture rearrangement required. Assign groups to zones using a rotation chart displayed on the blackboard. Each zone should have a laminated instruction card and all required materials pre-positioned before the period begins.

Materials: Laminated station instruction cards with must-do task and extension activity, NCERT-aligned task sheets or printed board-format practice questions, Visual rotation chart for the blackboard showing group assignments and timing, Individual exit ticket slips linked to the chapter objective

• Remember
• Understand
• Apply
• Analyze
• Self-Management
• Relationship Skills

Experiential Learning

⏱ 25 min·Pairs

Pairs: Ray Diagram Drawing

Provide worksheets with mirror outlines and object positions. Pairs draw principal rays: parallel to axis, through focus, to pole. Label image properties and discuss how rays change for concave versus convex. Share one diagram per pair with class.

Prepare & details

Explain the uses of concave mirrors in headlights and shaving mirrors.

Facilitation Tip: While pairs draw ray diagrams, remind students to use a ruler and label the principal axis, focal point, and object position for accuracy.

Setup: Flexible classroom arrangement with desks pushed aside for activity space, or standard rows with group-work stations rotated in sequence. Works in standard Indian classrooms of 40–48 students with basic furniture and no specialist equipment.

Materials: Chart paper and sketch pens for group recording, Everyday household or locally available objects relevant to the concept, Printed reflection prompt cards (one set per group), NCERT textbook for connecting activity outcomes to chapter content, Student notebook for individual reflection journalling

• Apply
• Analyze
• Evaluate
• Self-Awareness
• Self-Management
• Social Awareness

Experiential Learning

⏱ 30 min·Whole Class

Whole Class: Application Simulation

Use a torch and concave mirror to demonstrate headlight beam focus on a wall. Switch to convex mirror for rear-view simulation with toy car. Students predict and observe field of view differences, then note in notebooks.

Prepare & details

Analyze why convex mirrors are preferred as rearview mirrors in vehicles.

Facilitation Tip: For the Application Simulation, ask guiding questions like, 'What happens if the object moves closer to the mirror?' to deepen thinking.

Setup: Flexible classroom arrangement with desks pushed aside for activity space, or standard rows with group-work stations rotated in sequence. Works in standard Indian classrooms of 40–48 students with basic furniture and no specialist equipment.

Materials: Chart paper and sketch pens for group recording, Everyday household or locally available objects relevant to the concept, Printed reflection prompt cards (one set per group), NCERT textbook for connecting activity outcomes to chapter content, Student notebook for individual reflection journalling

• Apply
• Analyze
• Evaluate
• Self-Awareness
• Self-Management
• Social Awareness

Experiential Learning

⏱ 20 min·Individual

Individual: School Mirror Survey

Students locate concave and convex mirrors in school bathrooms, vehicles, or labs. Record image types formed and one application each. Compile class chart to discuss findings.

Prepare & details

Differentiate between the types of images formed by concave and convex mirrors.

Facilitation Tip: During the School Mirror Survey, ensure students sketch the mirror’s curvature first before predicting image properties to avoid rushed conclusions.

Setup: Flexible classroom arrangement with desks pushed aside for activity space, or standard rows with group-work stations rotated in sequence. Works in standard Indian classrooms of 40–48 students with basic furniture and no specialist equipment.

Materials: Chart paper and sketch pens for group recording, Everyday household or locally available objects relevant to the concept, Printed reflection prompt cards (one set per group), NCERT textbook for connecting activity outcomes to chapter content, Student notebook for individual reflection journalling

• Apply
• Analyze
• Evaluate
• Self-Awareness
• Self-Management
• Social Awareness

Teaching This Topic

Teachers often start with simple demonstrations before moving to hands-on work because spherical mirrors confuse students when explained only through theory. Avoid rushing into formulas; let students observe how images flip or shrink first. Research shows that students learn best when they sketch rays themselves and relate them to real objects like torches or rear-view mirrors.

What to Expect

By the end of these activities, students will confidently explain why concave and convex mirrors form different images and select the right mirror for real-life uses. They will also correct common misconceptions by comparing their own observations with ray diagram predictions.

Watch Out for These Misconceptions

Common Misconception

During Mirror Observation Stations, watch for students who assume concave mirrors always make images bigger. Ask them to move their hand closer and farther to observe changes in image size and position.

What to Teach Instead

During Ray Diagram Drawing, remind students that the object’s position relative to the focus determines image type. After pairs complete their diagrams, ask them to compare sketches with their station observations to correct the idea that concave mirrors always magnify.

Common Misconception

During Application Simulation, watch for students who think convex mirror images can be projected on a screen.

What to Teach Instead

During the School Mirror Survey, give students a small screen or paper and ask them to try capturing the image. When they see no projection, discuss why virtual images cannot be caught on screens.

Common Misconception

During Mirror Observation Stations, watch for students who believe convex mirrors show a narrower view than plane mirrors.

What to Teach Instead

During the School Mirror Survey, ask students to measure the angle of their field of view using a protractor held at arm’s length for both plane and convex mirrors to compare the coverage.

Assessment Ideas

Exit Ticket

After Mirror Observation Stations, provide two mirrors and ask students to fill a table recording image characteristics at different distances, checking if they link object position to image properties.

Quick Check

After Ray Diagram Drawing, show a concave mirror ray diagram on the board and ask students to identify the image type and characteristics based on the object’s position relative to the focus.

Discussion Prompt

During Application Simulation, pose the security camera question and ask students to justify their mirror choice using field of view and image clarity, listening for connections to convex mirror properties.

Extensions & Scaffolding

• Challenge students to design a periscope using one convex and one concave mirror, explaining how each mirror contributes to the image seen.
• For students who struggle, provide pre-drawn ray diagrams with missing rays and ask them to complete the path and label the image.
• Deeper exploration: Ask students to measure the focal length of a concave mirror using sunlight or a distant object and compare their results with standard values.

Key Vocabulary

Concave Mirror	A spherical mirror that curves inward, like the inside of a spoon. It converges parallel light rays to a focal point.
Convex Mirror	A spherical mirror that curves outward, like the back of a spoon. It diverges parallel light rays.
Real Image	An image formed by the actual convergence of light rays. It can be projected onto a screen and is typically inverted.
Virtual Image	An image formed where light rays appear to diverge from. It cannot be projected onto a screen and is typically erect.
Focal Length	The distance from the mirror's surface to its principal focus, where parallel rays converge or appear to diverge from.