Summary

In this lesson, students will learn about the chemistry of algae, while working in a small group to become an expert on a specific type of algae. Divided into four parts the lesson is designed for students to investigate the process of photosynthesis, learn about the variety of uses for algae as well as products that contain algae, and the harmful effects of algae, such as red tides. As a culminating task, student groups will each complete a short presentation.

Grade Level

Middle School

NGSS Alignment

This lesson will help prepare your students to meet the performance expectations in the following standards:

• MS-LS1-6: Construct a scientific explanation based on evidence for the role of photosynthesis in the cycling of matter and flow of energy into and out of organisms.
• MS-PS1-3: Gather and make sense of information to describe that synthetic materials come from natural resources and impact society.
• Scientific and Engineering Practices:
  • Engaging in Argument from Evidence
  • Obtaining, Evaluating, and Communicating Information

Objectives

By the end of this lesson, students should be able to:

• Describe the chemical reactions that occur during photosynthesis.
• Identify the chemicals responsible for the color of chloroplasts in algae.
• Describe at least one benefit of algae.
• Identify at least one negative aspect/hazard associated with algae.
• Explain how algae can be turned into products such as foods and alternative fuels.

Chemistry Topics

This lesson supports students’ understanding of:

• Chemical Reactions
• Photosynthesis
• Interdisciplinary Sciences

Time

Teacher Preparation: 30 minutes
Lesson: Four 40-minute parts

Materials

• Student worksheets
• 4-5 items that contain algae for demonstration only (examples: toothpaste, gum, nutritional supplements, bathroom cleaner, flip flops)
  • Note that “algae” in these items may be listed as spirulina, algin, or carrageenan.
  • If you are unable to obtain items, pictures are a good alternative option.
• 4-5 items that do not contain algae for demonstration only (examples: wooden pencils, electronics, items made from metal, etc.).
  • If you are unable to obtain items, pictures are a good alternative option.
• Online sources (linked individually throughout the Teacher Notes section)
• Presentation software (Google slides, PowerPoint, Canva, etc.)

Safety

• No specific safety precautions need to be observed for this lesson.

Teacher Notes

• This lesson was created as part of the 2023 Chemists Celebrate Earth Week (CCEW) Lesson Plan Contest. CCEW is celebrated the week of April 16–22, 2023 with the theme, “The Curious Chemistry of Amazing Algae.” Through this theme, students, teachers, and all those interested are encouraged to explore Algae. Emerging as one of the most promising long-term, sustainable sources of food, feed, and other co-products, algae are extremely important both now and for our future.
• If access to online sources is limited, the teacher can create a printed packet of information from the online sources for each of the various types of algae.

Classroom management tips

• This lesson was designed to be completed in four 40-minute parts/classes but can be modified as needed based on the teacher’s needs.
• The activity portions are designed to be completed by small groups of 3-4 students.
• Teachers can modify the list of algae types. For example, rather than exploring all eight types of algae, the types of algae being researched can be limited.

Lesson Instructions

Part 1: Algae and Photosynthesis

• Begin the lesson by asking students to list characteristics of algae and the source of their knowledge about the characteristic. For instance, a student may write that algae is green and they think it is green because they saw it in a fish tank. Students can record their thoughts on the introductory section of the student worksheet. Alternately, students could do this on a sheet of paper or on a virtual document. Students should initially work on the list on their own as a way to activate each student’s prior knowledge.
• Once the students have had an opportunity to list characteristics of algae, ask for volunteers to share their characteristics with the class. The teacher can generate a class list of characteristics on chart paper or electronically. The list should be saved so additions can be made to it throughout the lesson.
• After discussing the list of characteristics shared by the students, explain that the class will be editing and adding to their list as the class discusses algae.
• Show the students pictures of algae. The Algae Identification Guide from Florida Gulf Coast University and the Algae ID Guide from the National Institute of Water and Atmospheric Research Ltd. in New Zealand include a wide range of labeled pictures of different types of algae. If students think of new characteristics of algae after viewing the pictures, add them to the list.
• If the class did not already note that algae is a living organism, explain that algae is living. Show this short video (Definitions in the Field: Algae (0:55)) and ask students to see if they are able to confirm any of the algae characteristics they listed or if they learn about new characteristics from the video.
• After showing the video, update the algae characteristics list as needed.
• Ask the class how algae get the energy they need to survive. From the video, students should identify that algae go through photosynthesis. Photosynthesis is a chemical process that algae use to produce the glucose they need for survival.
• Ask the students to share what they already know or learned in the video about the substances algae take in to conduct photosynthesis.
• Explain that algae need sunlight, carbon dioxide, and water in order to photosynthesize. When plants go through photosynthesis, they produce glucose and oxygen.
• The equation for photosynthesis should be shared with students either electronically or on the board: 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂
• Explain the equation to students by pointing out that C is the chemical symbol for carbon, O is the symbol for oxygen, H₂O represents water and C₆H₁₂O₆ represents glucose. It is also important to discuss the number of atoms of each element that are present on each side of the equation, demonstrating the law of conservation of mass. Explain that while sunlight is not included on the equation, it is important because it serves as the energy to power the reaction.
• This website, Illuminating Photosynthesis, can be used as a demonstration or explored by students on their own to help illustrate the photosynthesis process.
• After reviewing the process of photosynthesis, remind the students that chlorophyll helps algae absorb the light it needs to conduct photosynthesis and chlorophyll gives some algae its green color. Tell the students that there are different types of chlorophyll in algae. Explain that algae come in a variety of colors, so there are also other pigments in algae that result in its color. Specifically there are chlorophylls A, B, C, D, E, and F, as well as carotenoids and phycobilins. Information about the wavelengths absorbed and reflected by these pigments is located on the Fondriest Environmental Learning Center webpage.
• Tell the students that they will be working in small groups to learn more about a specific type of algae and what causes its pigmentation.
• Place the students into small groups and assign them a specific type algae from the list below or let the groups pick the type of algae they would like to research. Students will work in these groups for the next portions of the lesson and then share their findings with the class through a very short presentation.
  • Types of algae for groups to research:
    • Bacillariophyta (diatoms)
    • Charophyta (stoneworts)
    • Chlorophyta (green algae)
    • Chrysophyta (golden algae)
    • Cyanobacteria (blue-green algae)
    • Dinophyta (dinoflagellates)
    • Phaeophyta (brown algae)
    • Rhodophyta (red algae)
• Ask the students to use the two resources (Smithsonian Algae Classifications webpage and the Algae Identification Guide) to find information about the pigment in their assigned algae. Students may also record additional information about their algae, if desired.

Part 2: Uses of Algae

• Remind students that they are learning about different types of algae and explain that in Part 2 they will be learning about some of the different uses of algae, and products that contain algae. Ask the students to take out their worksheet and list three possible uses for algae. Based on the research from the previous day, students should have some ideas for how algae can be used.
• After providing time for students to list their responses, ask for volunteers to share their ideas.
• Once the students have shared their ideas, show them a variety of items—some contain algae while others do not. It would work best to have actual products, but you could also use pictures. Some of the items should be products that contain algae (gum, cosmetics, toothpaste, flip flops, etc.) and some of the products should be items that do not contain algae (these could be items like wooden pencils, electronics, etc.). Designate one side of a desk for items that contain algae and the other side of the desk for items that are not contain algae. Have volunteers use feedback from the class to place items on one side of the desk.
• After all of the items have been placed, explain that algae is used in a variety of materials including abrasives such as bathroom cleaners, cosmetics, food additives, nutritional supplements, fertilizers, plastics, and fuels. This article (6 Commercial Products You Probably Didn’t Know are Made from Algae) contains additional information and could be read with students.
• Tell students that researchers are exploring ways that algae can be turned into fuel. Show this video, Energy 101 – Algae to Fuels, and ask students to think of ways that using algae for fuel might be beneficial.
• Once the video is finished, lead a discussion by asking students about the benefits and potential drawbacks of using algae as fuel. Benefits include carbon capture, the development of a cleaner burning fuel while drawbacks include the cost to develop the fuel.
• As an alternative to the video or in conjunction with the video, students can read Start Your Engines with Algae.
• Tell the students that algae can also be used to make plastics. Show the first video, How Plastic Made with Algae can Clean Waterways (8 minutes). Ask students to identify the potential benefits and drawbacks of using algae to make plastic. The video, Flip-Flops Made from Plants and Algae can Help Reduce Plastic Pollution (7:22) could be shown in addition to the previous video or as an alternative.
• Read the article Edible Algae with students or have them read the article in their small groups. Discuss the article with the students by asking them to review the types of foods that contain algae.
• After viewing the videos and reading the articles about the items algae is used to make, revisit the items the students placed into algae/not algae sections and ask the students if any items should be moved to a different side of the desk. Make adjustments to the items as needed.
• Ask the students to think about all of the different uses of algae and to complete questions two and three on their worksheet. If time allows, students could be encouraged to share their responses with the class.
• Have students return to their groups and research the benefits and potential uses of their assigned algae. Students can use the resources above and the Britannica website in their research. They can also use this site (Kids Britannica) to find more information.
• Groups should add the new information to their worksheet and can begin working on the development of a presentation to share with the class (see guidelines on student handout).

Part 3: Hazards of Algae

• Review Part 1 and 2 by asking students to share out some of the benefits of using algae and some of the products that can be made of algae. Spend some time revisiting their initial characteristics list and add characteristics as needed.
• Explain that while there are several benefits of algae, algae can also present problems and challenges.
• Ask the students to list some potential dangers of algae. Once they have had time to write down potential dangers, ask for volunteers to share their responses with the class.
• One of the hazards of algae is the toxins they can produce. Read this article aloud (Bad Blooms: Algae Gone Wild) with the students.
• After reading, discuss the Part 3 questions on the worksheet and have students write their responses..
• Tell the students they will be working in their groups to research potential dangers of their assigned type of algae.
• Groups can continue working on the development of a presentation to share with the class (see guidelines on student handout).

Part 4: Algae Presentations

• Prior to this day, the students should have completed their algae presentations.
• Give each student a Presentation Listening Guide worksheet to complete during each presentation.
• Have each group present their information. It may be helpful to provide students with a time limit for their presentations.
• Conclude the lesson by revisiting the class list of algae characteristics with the students and having the students respond to the last question on the listening guide.

Additional Resources

• The Britannica website provides a variety of information about algae and can serve as a source of background information for teachers.
• A variety of images of algae is located on the Smithsonian Ocean webpage.
• This AACT lesson plan, The Building Blocks of Photosynthesis, provides additional information on the chemical processes that occur during photosynthesis while this AACT lab, Investigating Photosynthesis, provides instructions for a teacher demonstration to provide an understanding of the process of photosynthesis.
• This activity (Transforming Gels) can be used as a hands-on extension to explain the use of algae in food.