Author: Chuck
Title:
Subject:
Grade :
Lens Ray Diagrams POGIL Activity
Light and Optics (Physics)
11 & 12
Description: Students are assigned one of four positions in collaborative learning groups.
Each student is a facilitator, spokesperson, recorder, or equipment manager.
The concept being investigated in this activity is drawing ray diagrams for lenses.
By comparing and contrasting two models of ray diagrams, one for mirrors and one for lenses, the students formulate answers to guiding questions related to the construction of lens ray diagrams. After successfully answering the questions the students complete a set of lens ray diagrams independently.
Length: one class period
Objectives: The students will be able to:
1.) Draw lens ray diagrams to locate images both real and virtual
2.) Label optical terms in ray diagrams
3.) Describe images as virtual/real, upright/inverted, larger/smaller
Materials: 1.) eight sets of laminated job cards (facilitator, spokesperson, recorder, manager)
2.) activity directions handouts
3.) textbook illustrations (two models)
4.) lens ray diagram drawing worksheets (to be completed independently)
Procedure: 1.) organize class into collaborative groups of four
2.) groups decide on answers to activity handout, “Lens Ray Diagrams”, questions
3.) instructor carefully monitors groups' activities to construct appropriate concepts
4.) upon successful completion of handout questions students complete ray diagrams
Explanation: Prior to this activity the students have learned how to draw light ray diagrams for mirrors through more traditional methods (lecture and demonstration). In this lesson they compare and contrast two models for drawing ray diagrams and discover for themselves how the "light ray rules" apply to lenses just as they do to mirrors. This type of inquiry learning should result in a deeper understanding of optical properties and improved retention for the students.
Assessment: As students proceed through the first handout of questions the instructor carefully monitors this process to eliminate potential misconceptions. All students within a group should agree on their answers since they were constructed collectively.
Then the ray diagram sets, which are completed independently, are scored for correctness.
Kansas Science Standards:

Standard 1, Benchmark 1, Indicator 4: The student actively engages in conducting an inquiry, formulating and revising his or her scientific explanations and models (physical, conceptual, or mathematical) using logic and evidence, and recognizing that potential alternative explanations and models should be considered.
Standard 2B, Benchmark 3, Indicator 4: The student will understand the principles of reflection and refraction.
Lens Ray Diagrams
Refer to the ray diagrams for lenses and mirrors on pages 534 and 571 in your textbook.
1.) What do the red arrows in the drawings represent?
2.) What is the minimum number of red arrows required to locate an image?
3.) Both mirror and lens ray diagrams have dark lines that bisect either the mirror or lens.
What is this line called?
4.) What does the letter F stand for in the mirror diagrams?
5.) Mirror diagrams have one focal point. How many focal points do lens ray diagrams have?
6.) In mirror diagrams there is a point called C, which is equal to twice the distance of F to the vertex. Do lenses have a similar point(s)? How are these points labeled on lenses?
7.) When a ray parallel to the principal axis strikes a converging mirror, what point does it reflect through?
8.) When a ray parallel to the principal axis passes through a converging lens, what point does it refract through?
9.) If an object is placed in front of them, farther away than point F, what do the images of converging mirrors and lenses have in common?
10.) If an object is placed exactly at point F in front of them, what do the images of converging mirrors and lenses have in common?
11.) If an object is placed closer to a converging mirror or lens than point F, what do their images have in common?
Check with your teacher when you think you have correctly answered the questions above. Then draw lens ray diagrams for the first three situations on the "Lens Ray Diagrams" handout.