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1. Comparing Lenses and Mirrors
Additional Teacher Instructions
Carolyn Crapo, IT 6515, Summer 2008
Lesson Plan - Day 1
Warm-up: Students will complete the pretest as a warm-up.
Teacher Presentation: Present information about curved mirrors. Topics to discuss
should include:
• How images are formed
• Definitions of principle axis, vertex, real image, virtual image, magnification, etc.
• Definition of the focus and how it relates to the curvature of the mirror
• The difference between concave and convex mirrors
• How to draw ray diagrams for both concave and convex mirrors
• How to solve math problems using the mirror/lens equation and the
magnification equation
• Sign conventions for heights, distances, etc.
Guided Practice: Give students time to practice drawing ray diagrams for convex mirrors
and the various cases of concave mirrors. Be sure they try the following concave cases in
which the distance between the object and the mirror is:
• Greater than twice the focal length
• Exactly twice the focal length
• Between one and two focal lengths
• Exactly one focal length
• Less than one focal length
Homework: A WebAssign assignment that allows students to independently practice
drawing ray diagrams and solving math problems for concave and convex mirrors with
immediate feedback.
Lesson Plan - Day 2
Warm-up: Have students draw a ray diagram for a concave or convex mirror.
Virtual Lab Activity: Students will pair up and check out a laptop from the laptop cart.
Give students the lab handout, “Converging and Diverging Lenses Virtual Lab,” and
walk around the room during the virtual lab answering questions as needed. This should
take the majority of the period.
Homework: Students should begin the comparison matrix on the back page of the lab
handout. They can begin on this at the end of the period if they finish early.

2. Lesson Plan - Day 3
Warm-up: Check that students have attempted the comparison matrix and stamp those
that have. Then have students get into groups of 3 or 4 and share their comparison
matrices and discuss the similarities and differences they found.
Teacher Presentation: Review the virtual lab together as a class and make sure the
students understand the properties of lenses. Discuss the procedure for drawing ray
diagrams for lenses and help the students draw at least one diagram for diverging lenses
and a few for converging lenses. Go over how to solve math problems for lenses, making
sure to focus on the sign conventions.
Group/Individual Practice: Have students practice ray diagrams and math problems for
mirrors and lenses using WebAssign. If possible, let the students use the laptops from the
laptop cart to check their answers. If not, they can check them on the classroom
computers. Students can either work alone or in groups of up to four students.
Homework: Give students a list of characteristics they need to include in their
comparison matrices. For homework, they should add those characteristics they don’t
have in their matrices and finish their class work assignment if needed. Characteristics
could include: focus/focal length, types of mirrors/lenses, rays drawn, types and location
of images formed, sign conventions and methods for solving problems with math.
Lesson Plan - Day 4
Warm-up: Students will complete a pre-lab quiz
Lab Activity: Show students the materials they will be using for the lab. Make sure to
discuss safety to prevent broken mirrors and lenses and because of the use of candles.
Take the students outside to measure the focal lengths of the converging lens and concave
mirror. Have all the students begin on the mirror part of the lab because it needs to be
very dark and using candles as light sources allows for that. Then once almost everyone
is done with the mirrors, students can begin the lenses part using the light bulbs as light
sources. It should take the entire period for the students to perform the lab. If they finish
the data taking before class is up, they can work on their write-ups.
Homework: Finish lab write-up, and find an article that gives a real-life example of how
curved mirrors or lenses are used in real life. Bring in the article and a one paragraph
summary of the application you found and how it relates to the concepts we’ve studied in
class. To help you begin your search, if you go to Wikipedia and look at the lenses or
mirrors articles, they both have ideas of practical applications. (The lenses one is better
though). Also, if you go to www.howstuffworks.com and search for lenses or mirrors,
you’ll get some ideas of some practical applications. Then you can search for
information on these applications.