Students learn about the advantages and disadvantages of the greenhouse effect. They construct their own miniature greenhouses and explore how their designs take advantage of heat transfer processes to create controlled environments. They record and graph measurements, comparing the greenhouse indoor and outdoor temperatures over time. Students are also introduced to global issues such as greenhouse gas emissions and their relationship to global warming.
Each TeachEngineering lesson or activity is correlated to one or more K-12 science, technology, engineering or math (STEM) educational standards.
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- Colorado: Math
- Colorado: Science
- b. Use appropriate measurements, equations and graphs to gather, analyze, and interpret data on the quantity of energy in a system or an object (Grades 9 - 12)  ...show
- a. Develop, communicate, and justify an evidence-based scientific explanation that shows climate is a result of energy transfer among the atmosphere, hydrosphere, geosphere and biosphere (Grades 9 - 12)  ...show
- Common Core State Standards for Mathematics: Math
- International Technology and Engineering Educators Association: Technology
- Next Generation Science Standards: Science
- Evaluate or refine a technological solution that reduces impacts of human activities on natural systems. (Grades 9 - 12)  ...show
- List the benefits (cost saving, efficiency) of using a greenhouse.
- Explain the greenhouse effect in depth.
- Provide an in-depth explanation of the greenhouse effect.
- 6 acrylic or Plexiglas squares, approximately 10 to 12 inches (25 to 30-cm ) per side
- hot glue gun and glue sticks
- soil and plant
- clear, wide strapping tape
- Greenhouse Design & Testing Worksheet
- (optional) structural frame made of wood, metal or plastic
- saws, to cut acrylic or Plexiglas
|The ability of a medium to absorb radiation.|
|The recent trend of increasing world surface temperatures, thought to be caused by pollutants and their "entrapment" of heat.|
|A structure with transparent walls and roof used for the cultivation of plants under controlled conditions.|
|The warming of the Earth's surface due to greenhouse gases.|
|Gases that contribute to the greenhouse effect (mainly carbon dioxide, methane and water).|
|(noun) A representation of something for imitation, comparison or analysis, sometimes on a different scale. (verb) To simulate, make or construct something to help visualize or learn about something else (as a product, process or system) that is difficult to directly observed or experimented upon.|
|Energy that is radiated or transmitted in the form of rays, waves or particles.|
|The amount of light that passes through an object.|
- Step 1: Radiation and Transmittance — Almost all the heat within a greenhouse comes directly from the sun through radiation. This energy is radiated through the Earth's atmosphere and transmitted through glass (or other transparent material) to the interior of the greenhouse.
- Step 2: Absorption — Once energy from the sun reaches the inside of the greenhouse, it must be absorbed. It helps to have a surface that absorbs almost all the energy that hits it (for example, something dark; soil works well). Whatever is inside the greenhouse continues to absorb this energy.
- Step 3: Convection — Once energy is absorbed within the greenhouse, heat is transferred throughout the space through convection. Cooler air falls to the bottom and gets heated up by the absorbing surface, and the process repeats. Because convection is the way the rest of the greenhouse gets heated, it is important to tightly seal the entire structure. Even opening the door for a short period of time can significantly reduce the indoor temperature.
Before the Activity
- Gather materials.
- (optional) To save class time, pre-cut acrylic or Plexiglas squares.
- Make copies of the Greenhouse Design & Testing Worksheets, one per team.
With the Students
- Divide the class into groups of two or three students each.
- Provide each team with a worksheet.
- Have students sketch and build their model greenhouses (see Part 1 on the worksheets). Limit greenhouse sizes to about 1 sq ft (a 10 x 10-inch [25 x 25-cm] base is a good starting point). See Figure 1 for an example sketch with dimensions noted.
- Have students cut (or provide already-cut) pieces of acrylic or Plexiglas for the greenhouse bases, walls and roofs.
- Have students glue pieces together to form the base and walls of the house (do not attach the roof yet). They may use some form of structural members between the acrylic pieces, as depicted in Figure 1.
- Direct students to fill the bottom of the greenhouse with soil and a plant.
- Instruct each group to insert a thermometer somewhere inside. If the thermometer does not fit inside, it can extend out of one of the joints, as long as the overall structure is sealed.
- Next, have students attach the roof using tape as a temporary seal for one of the pieces (to allow access to the inside). Remind students to make sure any gaps are filled in and that the structure is air tight when they are ready for testing.
- On a sunny day, bring the class outside to test their greenhouses. Follow Part 2 of the worksheet for testing procedures. As a control, also record the ambient outdoor temperatures (outside the greenhouse) at each time interval.
- Once testing is complete, bring the class back inside to complete the graphing and analysis portions (Parts 3 and 4) of their worksheets.
- Have students compare results with one another and discuss the overall results as a class.
- Conclude by continuing the class discussion, incorporating questions provided in the Assessment section. If time permits (or as a homework assignment), ask students to re-engineer their model greenhouses, as described in the Assessment section.
- Careful with the saws, hot glue guns and hot glue.
- What kind of heat transfer does a greenhouse use to gain heat? How is it able to do this? (Answer: The greenhouse gains heat through solar radiation. It is able to do this because radiation does not require a medium and can easily be transmitted through transparent or nearly transparent materials [such as glass].)
- What kind of heat transfer does the greenhouse prevent (between the inside and outside)? How does this help the greenhouse operate? (Answer: The greenhouse prevents convection heat transfer between the indoor and outdoor air. This allows the indoor air to be heated up while keeping it from exchanging with the cooler outdoor air. Because the greenhouse is sealed up, it only loses heat through conduction.)
Activity Embedded Assessment
- Why is it important for engineers to understand the principles behind which a greenhouse operates? (Answer: An understanding of the way greenhouses work helps engineers design structures for optimal energy efficiency.)
- How does the inclusion of a greenhouse add to the energy efficiency of a house? (Answer: Including a greenhouse in the design of a house enables additional solar energy to be harnessed and used for anything from growing plants to space heating in the winter season. The addition of a greenhouse has the potential to save a great deal of money and energy in any household.)
- For younger students, offer the worksheet's final analysis math calculation as a challenge question.
Greenhouse Effect. Updated December 4, 2008. Wikipedia, The Free Encyclopedia. Accessed December 4, 2008. http://www.gov.mb.ca/agriculture/crops/greenhouse/bng01s04.html
Greenhouse Heating and Venting: A guideline for determining heating and venting requirements of a greenhouse. March 2006. Manitoba Agriculture, Food, and Rural Initiatives. Accessed December 3, 2008. http://www.gov.mb.ca/agriculture/crops/greenhouse/bng01s04.html
The Vertical Farm Project - Agriculture for the 21st Century and Beyond. 2008. The Vertical Farm Project, Environmental Health Science of Columbia University, New York, NY. Accessed December 3, 2008. http://www.verticalfarm.com/
Landon B. Gennetten, Lauren Cooper, Malinda Schaefer Zarske, Denise W. Carlson
© 2007 by Regents of the University of Colorado.
Integrated Teaching and Learning Program, College of Engineering, University of Colorado Boulder
Last modified: November 26, 2015