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UTPA STEM/CBI Courses/Introduction to STEM/UV Sensitive Beads

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Course Title: Introduction to STEM

Lecture Topic: UV Sensitive Beads

Instructor: Javier Macossay

Institution: University of Texas - Pan American

Backwards Design

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Course Objectives

  • Primary Objectives- By the next class period students will be able to:
    • Understand the mechanisms of action of sunscreens.
  • Sub Objectives- The objectives will require that students be able to:
    • Identify the active ingredients in sunscreens.
    • Understand the mechanisms of action followed by the active ingredients in sunscreens.
    • Evaluate sunscreens with different protection factors (PF) and correlate this data with time of protection.
    • Understand the interaction between UV, radiation, and skin.
  • Difficulties- Students may have difficulty in the following:
    • -identifying the active ingredients in sunscreens.
    • -understanding the mechanisms of action of the active ingredients.
  • Real-World Contexts- There are many ways that students can use this material in the real-world, such as:
    • Sunscreen lotions are used to protect us from harmful UV radiation, which can react with our skin and promote skin cancer. Using the appropriate sunscreen will limit our exposure to UV radiation and protect our health.

Model of Knowledge

  • Concept Map
    • Identification of active chemicals in sunscreens.
    • Understanding UV radiation and interaction with chemicals.
    • Mechanisms of action of the active ingredients (dispersion and absorption).
    • Evaluation of different sunscreens by application on UV-sensitive beads.
    • Correlation of time of protection with sunscreen lotions with different protection factors (PF)
    • Determination of the most appropriate sunscreen lotions.
    • Understanding the interaction between UV radiation and skin.
  • Content Priorities
    • Enduring Understanding
      • Understand how to protect us from harmful UV radiation and the effect of this in health.
    • Important to Do and Know
      • The interaction of UV radiation with skin and matter. Mechanisms of action of active ingredients in sunscreens.
    • Worth Being Familiar with
      • Identification of chemicals.

Assessment of Learning

  • Formative Assessment
    • In Class (groups)
      • Discussion of active ingredients in sunscreens.
      • Discussion of UV interaction with active ingredients.
      • Discussion of individual laboratory procedures.
      • Discussion of results and conclusions.
  • Homework (individual)
    • Internet based search of sunscreen chemicals and formulations.
    • Internet based search of UV interaction with active ingredients.
    • Development of a laboratory procedure to test sunscreens with different PF. A correlation of time of protection vs. PF will be made. The surface on which they will be applied will be UV-sensitive beads.
    • Analysis of data and interpretation.
  • Summative Assessment
    • Discussion in front of the group of the conclusions.

Legacy Cycle

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LOOK AHEAD AND REFLECT BACK

  • Goals
    • Students should be able to understand the interaction between science and technology and real world applications and impact.
  • Objectives
    • Students should start identifying chemicals and learn the interaction of radiation with matter.

THE CHALLENGE

You have recently graduated from UTPA with a degree in Chemistry and have just taken your first job at The RGV Sunscreen Company. The company wants to develop sunscreen lotions that will be tested with spring breakers at South Padre Island next year. Your task is to compare and evaluate commercial sunscreen products in order to formulate a new line of products. The first approach is to use UV sensitive beads to evaluate the sunscreens. How do you perform this challenge?


GENERATE IDEAS

  • Students will independently research the chemicals found in sunscreens and the mechanism of action of the active chemicals.
  • Students will investigate the correlation between sunscreens with different PF and time of protection.

MULTIPLE PERSPECTIVES

Students will brainstorm then discuss their ideas before designing and performing experiments.

RESEARCH & REVISE

Once data is collected, students will discuss their results and draw conclusions.

TEST YOUR METTLE

Students will compare their results against recommendations provided by the sunscreens’ manufacturers.


GO PUBLIC

Students will discuss their results among themselves and in front of the class.

LOOK AHEAD AND REFLECT BACK

Based on students’ conclusions and interpretations, the experiment could be refined into individual brands of sunscreens. It could also be expanded to study the effect into several days.

Test Your Mettle Quiz

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True or False? (50 points)

  1. Water is an active chemical in sunscreens.
  2. Hydroxyacetone is an active chemical in sunscreens.
  3. The mechanisms of action in sunscreens are absorption and dispersion.
  4. Ethyl alcohol is an active chemical in sunscreens.
  5. Paraben is an active chemical in sunscreens.
  6. Zinc oxide is an active chemical in sunscreens.
  7. Mineral oil is an active chemical in sunscreens.
  8. The acronym PF means protection factor.
  9. Different sunscreen formulations might contain different chemicals but work as effective as one another.
  10. Hydroxyquinone is an active chemical in sunscreens.

Multiple choice (50 points)

11. UV sensitive beads are a good way to test sunscreen lotions because:

a) Beads are not useful
b) Beads do contain sunscreen lotion already
c) Beads contain UV-sensitive dyes
d) Beads interact with UV radiation
e) More than one of the above

12. UV sensitive beads change colors at the same rate (time) under the sun and in the lab, because:

a) It does not matter, UV radiation will reach the beads
b) The statement is not true, the beads change faster under the sun
c) The beads will change colors regardless of where they are placed
d) The statement is not true, the beads change faster in the lab
e) None of the above

13. Sunscreen lotions DO retard the time it takes the beads to change colors because:

a) No difference was observed experimentally with or without the use of sunscreen lotions
b) Lotions contain inactive chemicals that interact with radiation
c) Lotions contain active chemicals that interact with radiation
d) Lotions did not retard the time in any case
e) More than one of the above

14. Higher PF values ALWAYS results in lower UV absorption by the beads (longer times for the beads to change colors)

a) The statement is true
b) The statement is true for some PF values, but after a certain value, there is no difference
c) The statement is not true

15. Can the information learned in these experiments be used to understand how to prevent skin cancer?

a) Yes, because UV sensitive beads can be viewed as the skin
b) Yes, because the skin reacts with UV radiation similar to the way the beads react
c) No, because you cannot compare plastic beads to human skin
d) No, because the mechanisms of interaction between UV-beads and UV-skin are quite different
e) More than one of the above
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