lenses and light focus

Focus Light Energy with Lenses-

Instructional Objectives-Build the concept of Concentrating light energy, by redirecting sunlight with lenses, to Focus the light.
Time Required- 40 minutes
Advanced Preparation and prerequisite knowledge/skills- Use these sites to clarify the concepts and vocabulary of "controlling light". This one has a great discussion and plan for using lenses to make a super roasting oven.
Materials- Student instruction and recording sheet. Small hand lenses, and several types of paper (news-scrap, typing, wax, construction)
sets of several usable lenses can be purchased at Dollar stores.... I spent $7 for a class set.
Students can work alone or as partners.

Procedures:
This is another Challenge Activity. For fun you can inquire as to how they have used magnifying lenses. Some will have burned bugs or leaves..... some may think wider and bring out the idea of telescopes, microscopes, and good old glasses for seeing better.... the extensions are wide.

1. Partner the students.... they may each have a lense (better) or take turns. Each student records their own worksheet.Explain the challenge (write your initials, or whole name, by burning it into the paper.
2. Pass out small paper samples (paper clip together so they don't blow away) and raise the question as to whether different kinds of materials might heat up easier.... and how will you know? Inferences can be offered, then suggest they just TRY IT!
3. Find an undisturbed SUNNY place.... playground or benches, and circulate among the students while they figure out how to make it work. Certainly mention to the group when someone is particularly successfull.... with the idea that scientists share successes.... what material, what distance made the light brighter, etc.

PLEASE NOTE- Coach the students about the problem of the bright focused spot being hard on their eyes to look at for too long.... take breaks and work on your sheet/measurements with partner, discuss what works, then go back to do the quickest, most efficient method!