Exploring Science:

The Cognition and Development

of Discovery Processes.

Download Page


Table of contents

This web site

This web site contains all the programs and all the information that you will need to download and run the programs described in the book:

Klahr, D. (2000). Exploring Science:The Cognition and Development of Discovery Processes. Cambridge, MA: MIT Press.

In particular, you will find two programs: BT Lab and MilkTruck. The BT Lab is a program that will run both the Spaceship and Dancer microworlds. The MilkTruck program runs a variant of the MilkTruck microworld described in chapter 7.

By following the directions in this site, you will able to quickly and easily download these programs to either Macintosh or Windows systems. You can then run the programs to collect your own data, or run the programs as demos in a classroom. You may also modify the code to create your own versions.

We also have a QuickTime movie of a BigTrak subject that you can download.

The Programs (how to download, etc)

For Windows click here | For Mac click here

Windows users: Follow these steps

The Windows versions are self-extracting archives. Just double-click on the archive to extract the files; remember to select an appropriate directory in which to place the files. A readme file contains all the remaining instructions.

 BT lab

  • download the Windows version of BT Lab here



  • download the Windows version of MilkTruck here


Mac Users: Follow these steps

The Mac versions are StuffIt archives. If you have StuffIt Expander, the archives should automatically expand when you download them. If you don't have StuffIt Expander, go here to download a free copy. A readme file contains all the remaining instructions.

 BT lab

  • download the Mac version of BT Lab here



  • download the Mac version of MilkTruck here


About the programming language (cT)

The BT Lab and MilkTruck programs were written a programming language called cT. This language is a high-level language designed for rapid prototyping of educational and highly visual interfaces. One important advantage of cT is that a program can be developed for a Macintosh machine and easily ported to run on a Windows machine. Another important advantage of cT is that it is now freely distributed. We have made available the source code for BigTrak and MilkTruck. Thus, you can easily make modifications to the programs. However, we have designed the dowloadable materials such that you can just run the programs without looking at any source code, if that is what you prefer.

Read about the cT programming environment here.

Download the full cT programming environment (Windows, Mac, or Linux) here.

About the book

Einstein said that "the whole of science is nothing more than a refinement of everyday thinking." David Klahr suggests that we now know enough about cognition--and hence about everyday thinking--to advance our understanding of scientific thinking. In this book he sets out to describe the cognitive and developmental processes that comprise the body of information we can "scientific knowledge."

Over the past decade Klahr and his colleagues have conducted extensive laboratory experiments in which they create discovery contexts, computer based environments, to evoke the kind of thinking characteristic of scientific discovery in the "real world." In attempting to solve the problems psoed by the discovery tasks, experiment participants (from preschoolers through university students, as well as laypersons) use many of the same higher-order cognitive processes used by practicing scientists. Throug this work Klahr integrates two disparate approaches---the content-based approach and the process-based approach---to present a comprehensive model of the psychology of scientific discovery.

Click here to go to book pages at MIT press.


QuickTime movie of a BigTrak subject

Download full movie (warning: 8MB file)

Watch streaming QuickTime movie (warning: 3.9MB file)

Download zipped or stuffed versions (warning 3.7MB files)

This movie is taken from the original video-tape record upon which the protocol in Appendix 5.1 is based. It captures the "moment of insight" of an 11 year old girl as she figures out how the RPT command works. The original tape has been edited to keep the size manageable. The portion shown here corresponds to Experiments 9 through 16 (pp. 124-126), of Exploring Science. (Note: the annoying beeping that is heard a few times over the girl's verbalizations comes from BigTrak's "reminder" that it is awaiting further instructions.)

Technical notes: The QuickTime movie was created by transferring the original VHS video tape to digital format, and then editing that with iMovie, and then saving the movie in QuickTime format. The file is approximately 4M, and the running time is approximately 4 minutes. The streaming version is recommended if you have a slower connect and want to see the movie immediately as it is coming in. The compressed versions are only slightly smaller but may save you some trouble in controlling where the movies are placed on your hard disk.


The BT and Dancer microworlds were designed by David Klahr, programmed by Philip Lee and Matthew Day, and then substantially enhanced by Christian Schunn. The MilkTruck microword was designed and programmed by Christian Schunn. Thanks to Bruce Sherwood and Dave Andersen for cT help and advice at various stages of the project.

This site was developed by Christian Schunn
For simple questions, feel free to email me. However, I will not be able to do complex debugging or programming for you.

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