Nanoparticles and Sunscreen Ultraviolet Protection Investigation

Here is another project I expect to pilot in the classroom late winter or spring.  There is a wealth of information on the topic at http://nanosense.sri.com/activities/clearsunscreen/index.html  Enough information in fact to fill an entire semester!  Two resources that really grabbed my attention include the ChemSense animation software at http://chemsense.sri.com/download/and the Analyzing Digital Image software at http://www.umassk12.net/adi/

But the real star of this project are these UV sensitive beads.  They can be purchased online.  Here is a pic showing before/after exposure to UV light

UV beads

http://www.arborsci.com/uv-beads-package-of-1000?gclid=CPfUhOKD68kCFZEXHwodDk4Kiw

I expect to spend about 2 weeks in the classroom using Sunscreen and UV light as context for teaching first year chemistry.  Below you will find a somewhat detailed lesson plan.

Goal: The goal of this project is create a rich context for learning that engages students in an authentic research task that is relevant to public health as well Earth’s ecology and environmental sustainability.

Rationale: Secondary science education in the past has tended to emphasize content knowledge (“standards”) with little attention given to context—the questions, problems, and issues that make scientific knowledge and skills relevant to the real world and meaningful to students. This investigation will afford students the opportunity to learn numerous content objectives while also gaining insight into the methods and skills of the scientist in the broad context of links between human health and exposure to ultraviolet radiation.

Objectives:
1) Students will gain experience working in collaborative teams by performing a guided inquiry experiment.
2) Students will quantify the UV blocking capacity of various materials based on a color change using UV sensitive beads and “Analyzing Digital Image” (ADI) software.
3) Students will use experimental data to support their claims as to how different wavelengths of light energy interact with different types of matter.
4) Students will interpret and communicate the results of their research in a written report and an oral presentation.
5) Students will be able to describe and explain, using graphical representations and models, a) the electromagnetic spectrum, b) the ecological interaction of ozone in the stratosphere, and c) how particle size and atomic/molecular structure determines whether electromagnetic energy of a given wavelength (frequency) will be transmitted, absorbed, or scattered by the material.

Next Generation Science Standards:
• HS-PS2-6. Communicate scientific and technical information about why the molecular-level structure is important in the functioning of designed material.
• HS-PS4-3. Evaluate the claims, evidence, and reasoning behind the idea that electromagnetic radiation can be described either by a wave model or a particle model, and that for some situations one model is more useful than the other.
• HS-PS4-4. Evaluate the validity and reliability of claims in published materials of the effects that different frequencies of electromagnetic radiation have when absorbed by matter.
• HS-ESS3-6. Use a computational representation to illustrate the relationships among Earth systems and how those relationships are being modified due to human activity.
• Science and Engineering Practice 3 Planning and Carrying Out investigations.
• Science and Engineering Practice 4 Analyzing and Interpreting Data.
• Science and Engineering Practice 7 Engaging in Argument from Evidence.
Instructional Strategies:
• Internet Research—Students will research background information on the links between human health and exposure to the sun’s radiant energy, particularly UV energy. They will write a brief background statement (5 paragraphs and at least 2 supporting figures containing some type of data). The final draft background statement will be submitted as an introduction to a full lab report.
• Direct Instruction—The instructor will present additional information on the topic to fill in any gaps in basic knowledge, answer questions, and provide an overview of the materials and methods to be used in research. (PowerPoint: Sun Protection Understanding the Danger)
• Guided Inquiry—Students will be provided with the question to be addressed, materials and methods.
• Cooperative Learning—Students will work in small groups adopting the role of either a) project manager, b) equipment technician, b) data manager.
• Presentation—Research teams will present a poster summary of their results in class. Each team member will have a specific role during their presentation, as follows:
 Project manager will provide a summary of the overall purpose, methods, and research conclusions.
 Equipment manager will explain the function of the research equipment utilized during the project.
 Data Manager will explain the tables, graphs and other graphic representations of data.

Materials:
• UV Lamps
• UV sensitive beads
• Acetate film
• A variety of sunscreens (some containing nanoparticles), tanning lotions, fabrics, lenses, and transparent or semitransparent materials.
• ADI Software
• Digital Camera

Resources:

• ADI Software: http://www.umassk12.net/adi/
• Educational Innovations http://www.teachersource.com/ (for purchase of UV beads, UV lamps)
• Nanosense activities Clear Sunscreen: How Light Interacts with Matter web resources available at: http://nanosense.sri.com/activities/clearsunscreen/index.html

Activities
• Student Research (2 class periods; a draft background statement will be due on day four).
• Student preliminary presentations (1 class period)
• Instructor Presentation/Project Overview (1 class period)
• Preparation of a standard reference scale using ADI software and UV beads (1 class period). (UV beads will be exposed to UV light and photographed at 1 second intervals from no exposure to fully exposed).
• Data Collection (1 class periods). Most likely monitor ozone in the vicinity of the morning bus drop offs.
• Data Analysis using ADI software (1 class period).
• Report Write Up and Oral Presentations (4 class periods).
• Assignments: Text based readings with practice questions covering a) the electromagnetic spectrum, b) atomic/molecular structure and quantized energy interactions, and c) nano-particles why size matters.

Extension:
• The investigation may be performed qualitatively based on ranking the visible color change using a reference scale (photographs of UV beads at varying degrees of exposure). This approach has the advantage of simplifying the research methods, allowing students to focus on essential concepts. It also cuts the total time commitment by roughly half.
• As an extension, the project may be performed quantitatively by analyzing pictures of experimental results and comparing to the reference scale photographs using ADI software.
• Special Education: Specific to the needs of individuals based on IEP accommodations. Research teams will be chosen to maximize diversity within student groups. Project managers will be responsible for helping to assist other team members, as needed on a case by case basis.

Assessment:
• Individual lab reports including background research.
• Oral Presentations.
• Test (multiple choice and open response).