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Lesson: That (Motion) Captures It!


(Adapted from from the Integrated Teaching and Learning Program, College of Engineering, University of Colorado at Boulder.)


In this activity, students in grades 5 – 7 learn how motion capture technology (mo-cap) enables computer animators to create realistic effects. They learn the importance of center of gravity in animation and how to use the concept in writing an action scene. As an extension, students can use free, down-loadable software to animate their scenes.

Note: The literacy activities are based on physical themes that have broad application to how humans experience the world  — concepts of rhythm, balance, spin, gravity, levity, inertia, momentum, friction, stress and tension.

Grade Level: Grades 5 – 7    

Time: 120-160 minutes (two 50-minute classes, plus one to three sessions to discuss and critique action scenes)

Pre-requisites: General familiarity with the concepts of center of mass, center of gravity, balance, and gravity.

Engineering Connection

People have an intuitive sense about balance, so computer animation designers who want to create realistic effects must convey a convincing sense of balance in their work.  Authentic-looking special effects, such as collapsing bridges or exploding structures, must first convey a loss in equilibrium before they fail. Engineers also must be convincing communicators. When writing to persuade, it is sometimes helpful to catch the reader off balance to make a dramatic point!

Learning Objectives

After doing this activity, students should be able to:

  • Use a full range of strategies to comprehend technical writing, newspapers, magazines, poetry, short stories, plays and novels.
  • Choose vocabulary and figures of speech that communicate clearly.
  • Learn the importance of center of gravity in animation and how to use the concept of center of gravity in writing an action scene.


International Technology Education Association

C. Various relationships exist between technology and other fields of study. [Grades 3 – 5]

Common Core State English Language Arts  Standards   

  • W.5.3 Write narratives to develop real or imagined experiences or events using effective technique, descriptive details, and clear event sequences. [Grade 5]
  • W.6.5. With some guidance and support from peers and adults, develop and strengthen writing as needed by planning, revising, editing, rewriting, or trying a new approach. [Grade 6]
  • W.6.6. Use technology, including the Internet, to produce and publish writing as well as to interact and collaborate with others; demonstrate sufficient command of keyboarding skills to type a minimum of three pages in a single sitting. Orient the reader by establishing a situation and introducing a narrator and/or characters; organize an event sequence that unfolds naturally.
  • Use narrative techniques, such as dialogue, description, and pacing, to develop experiences and events or show the responses of characters to situations.
  • Write narratives to develop real or imagined experiences or events using effective technique, relevant descriptive details, and well-structured event sequences.
  • Engage and orient the reader by establishing a context and introducing a narrator and/or characters; organize an event sequence that unfolds naturally and logically.
  • Use narrative techniques, such as dialogue, pacing, and description, to develop experiences, events, and/or characters.
  • Use a variety of transition words, phrases, and clauses to convey sequence and signal shifts from one time frame or setting to another.



In addition to being important for human equilibrium and balance, center of gravity can make the difference between convincing and unconvincing computer animation. The first “Spiderman” and “The Incredible Hulk” movies were criticized for their unconvincing sense of real motion; the characters were too gravity-defying. To be realistic, even high-flying movements have to convey a sense that gravity is still having an effect. Animated characters have to give the impression of having a center of gravity.

In this activity, students explore the concept of center of gravity by learning about the emerging field of motion-capture (mo-cap) in computer animation and special effects. They also learn how important the concept of a center of gravity is in hand-drawn action art and animation. Finally, they apply the concept of a “center of gravity” as a way to organize a written fantasy action sequence.

Watch 3-D motion capture techniques developed by Max Planck Institute researchers in 2009:


1. Observing

For background reading and research, see the References and Resources section (below) for several links to motion capture sites and videos. Or search the Internet using keywords such as motion capture, performance capture, optical motion capture, or motion capture video.

This quick, 5-minute “find the center of gravity” activity from San Francisco’s Exploratorium will help students develop a hands-on feel for the concept using a yardstick, clay or weight, and masking tape.

Carefully study Figure Drawing: Basic Pose and Construction by William Li, at the Fantasy Art Resource Project. It includes an excellent analysis of the concept of center of gravity as related to figure drawing. The author makes the point, “To construct something you must understand it.” This is as true of writing as it is of drawing.  

As a warm-up for writing your action sequence, you might want to experiment with the drawing techniques described. Your drawing ability is likely to improve along with your writing ability.

2. Thinking/Acting It Out

The title of this section could also be named “Experiencing.” Get in touch with your own center of gravity. That’s one of the best ways to prepare to write an action scene. Act out the scene and think through the motions as they are organized around the center of gravity. Do the same when observing how mo-cap is executed.

3. Writing

Now, write your action sequence. Again, the Fantasy Art Resource Project provides an excellent guide to  Writing Action by S. B. “Kinko” Hulsey. Follow the steps from “Bleh!” to “Better. Much better,” to “Wow, that captures it!”

Troubleshooting Tips

Clarify for students the difference between a complete sentence and a fragment. At this stage, it can be helpful for them to know when a fragment “works,” as in writing about action, and when it does not, as in writing a more formal essay. The distinction can help students control their use of fragment sentences. Plan on spending one or two 50-minute classes to introduce the concepts of motion capture, animation, and action-writing followed by two or three 20-minute sessions to critique drafts of the written action sequence.

Activity Extension

  • Make a computer animation of your action scene using free, down-loadable software for students and teachers.  Autodesk offers free versions of Maya, used in many Hollywood computer-aided graphics, and MotionBuilder to education community members. Teachers can download a demo version and see classroom examples of  SAM Animation, a stop-frame system developed at Tufts University’s Center for Engineering Educati0n and Outreach, at iCreate to Educate. Softronic offers several free programs, including the popular Pivot stick figures animator.
  • Learn how the Golum character in “Lord of the Rings” was “captured.” Use the keywords “Golum” and “motion capture” in Google. Report your findings to the class.
  • How about a career in computer animation using the latest in motion-capture technology? Chances are the field will have advanced considerably by the time you are ready for a career, but there is no time like the present to start learning about this exciting technology. See The Advanced Computing Center for the Arts and Design (ACCAD)‘s Motion Capture Lab for ideas. How many applications for motion capture can you count besides computer animation?

References and Resources

The website for the Motion Capture Lab at Ohio State University’s Advanced Computing Center for the Arts and Design (ACCAD) includes links to a history of motion-capture technology (from 1872 sequential photos of a galloping horse) and Project Gallery.

The University of Southern California’s Institute for Creative Technologies features videos made with virtual human mo-cap technology.

“Chemistry in the Kitchen,” a cartoon created by students from the Center for Advanced Spatial Technologies at the University of Arkansas, uses mo-cap animation to teach kids how yeast causes bread to rise.

Carnegie Mellon Graphics from Carnegie Mellon University has links to dozens of mo-cap projects, including video and embedded animated images.

New York University’s Movement Lab worked with the New York Times to create a 3-D interactive animation of pitcher Mariano Rivera to accompany a magazine feature “King of the Closers.” The lab has developed an iPhone app called Dot Show that uses its GreenDot technology to create an animated dot version of video.

Watch a GreenDot mo-cap demonstration on the Discovery Science channel’s Innovation Nation:

In this Wired video, Stanford University’s Biomotion Lab researchers explain how they use mo-cap to analyze the gait of people with arthritis and other mobility impairments.

Center of Gravity, Science Snacks from the Exploratorium, San Francisco, CA.

How motion-capture technology can measure human behavior. August 2010 BBC News video report of an unusual partnership between actors and University of Southern California engineering researchers to develop systems to help children with autism or couples undergoing marriage therapy.

“Avatar” Motion Capture Mirrors Emotion. Discovery News video with scenes from the making of “Avatar” and director James Cameron explaining how new technology allowed the characters to appear real in emotion as well as action.

Practical Motion Capture in Everyday Surroundings. YouTube video of MIT students’ motion-capture system is long on the electronics but includes some nifty side-by-side comparisons of real human walking or dancing and animated image.

Furniss, Maureen. Motion Capture. MIT Communications Forum.

Hulsey, S. B. “Kinko.” Writing Action. Elfwood Tutorials: Fantasy Art Resource Project.

Li, William. “Figure Drawing: Basic Pose and Construction.” Elfwood Tutorials: Fantasy Art Resource Project.

Contributors: Jane Evenson, Malinda Schaefer Zarske, Denise Carlson. © 2004 by Regents of the University of Colorado. Lesson and resources updated Nov. 1, 2011 by eGFI.

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