Daisyworld - This World is Black and White

This short, engaging video created by NASA presents a complex topic via a simple analogy. The idea of positive and negative feedback is demonstrated by Daisyworld - a world with black and white flowers growing on it.

Go To:

http://svs.gsfc.nasa.gov/cgi-bin/details.cgi

NASA

Sphere feature LOOP

Notes From Our Reviewers

The CLEAN collection is hand-picked and rigorously reviewed for scientific accuracy and classroom effectiveness. Read what our review team had to say about this resource below or learn more about how CLEAN reviews teaching materials

Teaching Tips

Consider using the terms self-reinforcing cycle instead of positive feedback, and self-muting feedback instead of negative feedback. Emphasize to students that these terms are related to mathematical processes, not emotional ones.

A lot of information is presented quickly. Educators may want to play it once all the way through, then again to stop/start and explain things.

This resource will enhance any lesson that is about the relationship between changes in biotic and abiotic variables.

Consider asking students to draw a causal loop diagram for each of the loops and see how they join together.

About the Science

The video illustrates the concept of albedo. Black daisies absorb solar radiation while white daisies reflect it. A change in atmospheric temperature drives a change in daisy population, which then drives a change in atmospheric temperature, and so on.

The concept of albedo is accurately described as the percentage of solar radiation that bounces off the surface (mirror = 100% reflected energy).

Comments from expert scientist: This is a very nice, short video explaining the concepts of albedo and feedbacks using Daisy World as an example. The video is accurate, easy to understand and well produced. It does a nice job of explaining how the Daisy World model relates to the real world.

About the Pedagogy

This video is a good adjunct to use in a lesson on feedbacks loops in environmental and climate systems. As this is a complex topic, it will need additional explanation by the teacher.

A potentially confusing element is the counter-intuitive nomenclature of positive vs negative feedbacks. Educators will need to review these concepts with students.

Technical Details

Good quality and easy to use. Transcript available.