Two interactive NetLogo models that make particle behavior — temperature, state changes, evaporation — tangible for middle school science students.
The primary goal was to help students visually comprehend and analyze particle behavior under varying temperatures, states of matter, and environmental changes — turning abstract scientific concepts into something they can manipulate and observe directly, as an introductory, hands-on tool in the classroom.
A container is divided into four zones — red, yellow, green, and blue. Sliders control the temperature of the red, yellow, and green zones directly, while the blue zone is governed by room temperature. Particle movement follows the Lennard-Jones potential, so particles interact based on distance and energy. Particles are color-coded by speed: faster (hotter) particles turn red, slower (cooler) ones stay blue — letting students watch temperature zones "sort" the particles in real time.
Things to notice — What happens when only one zone is set to the minimum or maximum temperature? Why?
This model shows water molecules transitioning from liquid to gas under varying temperature conditions. Adjustable temperature and firepower sliders, plus switches to open or close each container's lid, let students experiment directly with the rate and mechanics of evaporation. When a lid is open and firepower is high, particles clearly escape into the air faster than in a closed, unheated container — making the invisible process visible.
Both models are built on the Molecular Dynamics Lennard-Jones model (Kelter & Wilensky, 2022), giving the simulations real physical grounding rather than a simplified cartoon of particle behavior. The models are structured to encourage exploration — students manipulate variables and observe outcomes, supporting a progression from basic concept recognition to more advanced analysis and application.
Kelter, J. and Wilensky, U. (2022). NetLogo Molecular Dynamics Lennard-Jones model. Center for Connected Learning and Computer-Based Modeling, Northwestern University, Evanston, IL.
Wilensky, U. (1999). NetLogo. Center for Connected Learning and Computer-Based Modeling, Northwestern University, Evanston, IL.