Home PublicationsL&LIssuesVolume 37 (2009-2010) February (No.5)

Learning Connections

By Eric Klopfer, Hal Scheintaub, Wendy Huang, and Daniel Wendel

How will the ecology of Silver Lake change if an invasive species is introduced? Will the biodiversity be affected?

T o some, these sound like questions for a practicing scientist. To others, they address Massachusetts biology standards 6.2 and 6.3. For high school students learning to use the free modeling software StarLogo TNG (The Next Generation), they are the guiding questions for building a simulation that models the ecological concepts they are studying in class.

StarLogo TNG (http://education.mit.edu/drupal/starlogo-tng), created by the MIT Scheller Teacher Education Program (STEP), builds on the long Logo tradition of creating languages that make computer programming accessible, fun, and educational. StarLogo TNG is designed to make it easy for students and teachers to explore, modify, and even create computer simulations and games.

Why Simulations?

Many educators and scientists, including those at MIT's STEP, believe that to prepare the next generation of scientifically literate citizens and inspire students to pursue science, technology, engineering, and mathematics careers, the curricula must include the skills and knowledge of simulation science. Constructing and using computer simulations has been called "the third way of doing science," after traditional experimentation and observation/description.

Simulations have revolutionized modern science, allowing investigators to understand processes that happen across scales and in systems containing large numbers of interacting agents. Simulations help chemists see how interactions that are otherwise invisible at the molecular level are responsible for measurable physical characteristics of a substance. They are invaluable to an epidemiologist's understanding of how a disease spreads in a population. It is time for models and simulations to help chemistry, physics, and biology students see and understand the world in new and powerful ways.

Although studying scientific phenomena using simulations is powerful, it is not enough. Just as students cannot gain a complete understanding of a phenomenon by watching a video, they can't learn by merely manipulating the variables of a computer simulation. Real understanding comes through hands-on immersion in field or lab experiences or, even better, through designing one's own experiments in the inquiry process and not just following a step-by-step recipe to verify what's already known.

Painting with Blocks

At first glance, building simulations may seem like a daunting class activity. Most science teachers have not done much programming and rightfully worry about teaching these skills to a class. The task of debugging dozens of student programs would be problematic even for a skilled programmer. StarLogo TNG prevents a great deal of that trouble by using a graphical programming language that specifies the structure of the language using shapes that fit together like a jigsaw puzzle.

StarLogo TNG uses a painting metaphor for programming. You pick commands written on blocks that look like puzzle pieces from the palette. The commands are organized into categories. You select a category of commands to browse, and a drawer pops open with the available commands for that category. Once you find the command that you want, you drag it into the big programming area known as the canvas. You stack commands on top of each other to make procedures or parts of procedures, which you can connect later.

Each block is shaped so that it can be attached only to other blocks with corresponding shapes. A typical logical statement (an "if" statement) has a logical test and a list of commands to run if that test is true. In the first "if" statement of the "fly" procedure (Figure 1), the test is whether the "u" key on the keyboard is being pressed. If it is, then the object in the simulation that is controlled by that command will move upward 0.2 units. The number "0.2" has an angular shape, whereas the "keyboard u?" block has a rounded shape to show the student where they can and cannot be used. So who would move up 0.2 units and where would she move? The answer is the object that is on the screen in the 3D world called Spaceland in StarLogo TNG.

Figure 1: The StarLogo TNG programming interface consists of a palette of commands that students can place on the programming canvas.

Spaceland can be sculpted to suit the student or teacher's needs. It can be a rolling landscape, a world of walls, or a relatively flat plain.

Spaceland can be viewed from a third-person or a first-person perspective, as in Figure 2. As students toggle between the individual and global perspectives, they can see how the behavior of individual elements can have system-level effects.

Figure 2: A first-person perspective in StarLogo TNG shows the world from the view of an individual agent. In this case, it is a fish inside the ecosystem.

Teaching 2D Motion

Starlogo TNG can be used to model biological, chemical, and, as described here, physical systems.

After a short series of introductory lessons, students can use programming as a learning tool. The concept of simultaneous but independent change, which is central to understanding 2D motion, is difficult and frustrating to teach and learn. As part of a high school physics unit, students can program two-dimensional motion in a virtual world. Students begin the unit by programming simple and separate procedures with change- agent attributes such as color, size, and location. Students can press keys individually or simultaneously, producing many humorous combinations of change, such as animals changing size and color simultaneously.

They control motion by manipulating the distance that their creations cover in one time step. Students quickly recognize that the default value of "one step" represents the distance covered in a single iteration. By turning this constant into a variable, students experiment with velocity by creating a slider that changes that variable in real time and moves their creations at different speeds. By combining that movement in the x direction with a separate change in the y direction, they can experiment with independent simultaneous change of velocity in two dimensions.

The progression from simple manipulation to the advanced programming concept of variables moving both vertically and horizontally occurs naturally, as they are linked to the student's desire to create a variety of motions for their creations.

The culmination of the kinematics section is a unit on projectile motion. To get realistic vertical motion, students add to independent motions on the ground a procedure for the negatively directed acceleration of free fall in the z direction. A game can help students experience this hard-to-
picture situation (see Figure 3). Students build a jumping game by following a set of scaffolded instructions. The goal of the game is to get a raccoon to jump over a wall and hit a target. Students build procedures that produce forward motion at a constant velocity and vertical movement that employs acceleration. Although these are separate procedures, they can be executed simultaneously to demonstrate realistic motion.

Figure 3: Programming and executing the variables, acceleration due to gravity, g, and the vertical and horizontal components of the jump speed give students firsthand experience with the roles of these factors in determining how far and how high the raccoon jumps.

After completing this unit, a student wrote this reflection:

I really like this style of learning because it is not taking tedious notes. You get to demonstrate the concepts you are learning through simulations rather than just writing and reading.

StarLogo TNG can feasibly fit into a crowded science curriculum along a spectrum from students manipulating a prebuilt simulation model, to modifying a model, to designing and building their own models. TNG can leverage students' enthusiasm for playing and making games. As TNG continues to develop, look for an integrated means to share projects with an online community of StarLogo TNG users as well as other features that integrate the sciences of simulation and gaming. Find out more at http://imaginationtoolbox.org.

	Eric Klopfer is an associate professor and director of the MIT Scheller Teacher Education Program (STEP) and the Education Arcade. His work focuses on the research and development of games and simulations for learning.
	Hal Scheintaub, PhD, is a researcher in MIT's STEP and a developer for StarLogo as well as a secondary school science teacher. He was previously a postdoctoral fellow at the Albert Einstein College of Medicine and a public health research scientist.
	Wendy Huang, MS, is the program manager for MIT's STEP. She has also been a middle school math teacher, teacher educator, and educational software and curricula developer.
	Daniel Wendel, MA, leads the StarLogo TNG development team. He spends his time running workshops, developing materials, and helping teachers use StarLogo TNG in their classrooms.

Copyright © 2010, ISTE (International Society for Technology in Education), 1.800.336.5191 (U.S. & Canada) or 1.541.302.3777 (Int'l), iste@iste.org, www.iste.org . All rights reserved.

Learning & Leading with Technology | February 2010