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Let's Learn Science: Spectrophotometer Lesson Plan for 7th/8th Grades

The DU Spectrophotometer was introduced in 1941 by Arnold O. Beckman to measure the amount of ultraviolet light absorbed by a substance. It also provided a more accurate method of determining the chemical composition of complex substances while reducing the amount of time needed for analysis. Beckman’s spectrophotometer was extremely important during World War 2 when the U.S. military needed to produce higher octane gas. It was also an important tool in recognizing vitamin-A rich foods for soldiers.

We can better understand the importance of the spectrophotometer and how it works by creating a spectroscope using the following lesson plan.

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DU 1941_color.PNG

AMBF Collection Area: Spectrophotometer

Grade: Middle School (recommended 7th or 8th grade)

Subject Area: Science, English Language Arts

Duration: 1 hour

Lesson Objectives

  1. Students will be able to investigate different types of light sources and their properties when seen through a spectroscope
  2. Students will be able to describe a spectrophotometer and how diffraction grating of light allows this tool to work
  3. Students will be able to explain the difference between a spectroscope and a spectrophotometer

Learning Standards

Next Generation Science Standards:

MS-PS4-2 Develop and use a model to describe that waves are reflected, absorbed, or transmitted through various materials

MS-PS4.B Electromagnetic Radiation – When light shines on an object, it is reflected, absorbed, or transmitted through the object, depending on the object’s material and the frequency (color) of the light

Common Core State English Language Arts Standards:

CCSS.ELA-LITERACY.RST.6-8.3 Follow precisely a multistep procedure when carrying out experiments, taking measurements, or performing technical tasks

CCSS.ELA-LITERACY.RST.6-8.7 Integrate quantitative or technical information expressed in words in a text with a version of that information expressed visually (e.g., in a flowchart, diagram, model, graph, or table)

3D Modeling

Click here to see three dimensional digital modeling of the spectrophotometer.

Materials

  1. Small box (shoe box sized)
  2. 1 CD
  3. Aluminum foil
  4. Tape
  5. Scissors
  6. Pencil
  7. Coloring supplies (optional)
  8. Student Handout (Availabe in the Printable PDFs section)
  9. Various light sources (e.g fluorescent light bulbs, incandescent bulbs, indirect sunlight, element tubes, if available)

Printable PDFs

Classroom Activities

  1. Warm-up Discussion: Have you ever seen a rainbow? What makes a rainbow? What do you need to make a rainbow? Can you make one without rain?
  2. Pass out the Create Your Own Spectroscope Student Handout (Available in the Printable PDFs section) and read as a whole class or in pairs. Suggested comprehension questions:
  • What natural diffraction gratings can be used to make rainbows?
  • Describe the electromagnetic spectrum and what role does ROYGBIV play in relation to this spectrum?
  • What color is associated with short frequently occurring waves on the electromagnetic visible spectrum?
  • What is a spectrophotometer and who uses one?
  • Which light bulb is more energy efficient- incandescent or fluorescent light bulbs?

3. Discuss which light sources the students would like to observe. Have students share with their partners what they think each light bulb’s different wavelengths will look like when using the spectroscope.

4. In groups, have students follow the instructions and complete the spectroscope activity sketching their observations in the table and answering the questions.

5. As a whole class, discuss results and share as a class:

● What surprised you today?

● What is something new you learned?

Extension Ideas

● These videos explain how astronomers and chemists use spectra to determine the makeup of stars:

Video 1

Video 2 (first 3 mins are relevant to this lesson)

● Students bring in 3D glasses or diffraction grating slides to class and experiment with different light sources and compare these results with the spectroscope. Students can research and sketch a drawing of how 3D glasses work with light waves to explain how movies utilize this phenomenon to make special effects come to life.

● Students divide into groups and explore careers such as an oceanographer, x-ray technician, electronic engineer, and seismologist. Students will report back how these jobs depend on their knowledge of invisible waves to best serve their customers.

Additional Resources // Recursos adicionales

Read more about the spectrophotometer here or watch the videos below.

ESPECTROFOTÓMETRO

El espectrofotómetro DU fue presentado en 1941 por Arnold O. Beckman como un instrumento que medía la cantidad de luz ultravioleta absorbida por una sustancia. También ofrecía un método más preciso para determinar la composición química de sustancias complejas al tiempo que reducía la cantidad de tiempo necesario para el análisis. El espectrofotómetro de Beckman fue extremadamente importante durante la Segunda Guerra Mundial, cuando el ejército estadounidense necesitaba producir gasolina de mayor octanaje. La gasolina enriquecida a 100 octanos permitió a los aviones volar distancias más largas durante períodos más largos y llevar más armas y carga. El espectrofotómetro fue crucial para distinguir las fracciones del petróleo necesarias para obtener los hidrocarburos requeridos para enriquecer la gasolina.

El espectrofotómetro también fue útil en 2010 durante el derrame petrolero de la plataforma DeepWater Horizon. Un espectrofotómetro fue acoplado a un avión ER-2 y llevado por los cielos a través del Golfo de México para realizar mediciones sobre miles de millas de océano. El espectrómetro podía detectar sustancias químicas en áreas amplias y medir el espesor del petróleo en la superficie del océano para determinar si se estaba descomponiendo y cómo se estaba dando este proceso. Si bien el espectrofotómetro no podía reparar el derrame de petróleo, este instrumento ayudó a los científicos e investigadores a dar una respuesta más eficaz al derrame.

Sources // Contributors

This lesson plan was developed using inspiration and some source material from here, here, and here. Thank you to the following contributors and content curators: Christopher Gear, Alison Mondrach, M. Ed., Scott Pawlowski, Kaerie Ray, Kelsey Talbot, Nicole Zawadzki, and Mariana Zechini.