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Let's Learn Science: Spectrophotometer Lesson Plan for 6th Grade

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 learning more about diffraction grating in the following lesson plan.

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DU 1941_color.PNG

AMBF Collection Area: Spectrophotometer

Grade: Middle School (recommended 6th grade)

Subject Area: Science, English Language Arts

Duration: 45 minutes

Lesson Objectives

  1. Students will be able to investigate different types of light sources including incandescent and fluorescent light and their properties when transmitted through diffraction grating
  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 electromagnetic spectrum and identify where visible light is located

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. Each student group will have 3 light sources with one electricity source (Electrical outlet or battery) to investigate:

● Incandescent light bulb

● Fluorescent light bulb

● One light source of their choice (laser pointer, birthday candle, flashlight, camping lantern, etc.)

2. Each student group will have one Diffraction Grating Slide

3. Crayons or colored pencils

4. White paper

5. Ruler (optional)

6. Diffraction Grating Student Handout (Available under the Printable PDFs section)

Printable PDFs

Classroom Activities

  1. Warm-up Discussion: Make a list of different types of lights you see in a day. What type of light bulbs do you use at home versus school? Have you heard of incandescent or fluorescent light bulbs? What is the difference between an incandescent and a fluorescent light bulb?

2. Pass out the Diffraction Grating Student Handout and read as a whole class or in pairs. Suggested comprehension questions:

● What is diffraction grating?

● 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. Demonstrate how to shine light sources through the diffraction grating slide. Have students share with their partners what they think each light bulb’s different wavelengths will look like when using the diffraction grating.

4. In groups, have students follow the instructions and complete the diffraction grating 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

● Students bring in 3D glasses to class and experiment with different light sources when wearing 3D glasses and compare these results with the diffraction grating slides. 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.