In this activity, students explore phase change at a molecular level. They trace the path of an atom to view intermolecular interactions and investigate how temperature relates to phase change. Upon activity completion, students will be able to give examples of phase change, explain how the input of energy into a system affects the state of matter, and describe how both latent heat and evaporative cooling play a role in changes of phase.

Explore what happens at the molecular level during a phase change. The three common physical states of matter (also called phases) are solid, liquid and gas. Matter can change phase with the addition or subtraction of heat. Molecules are always in motion. The molecules in a solid move more slowly than those in a liquid. When molecules are heated, they gain kinetic energy (motion). Kinetic energy can be transferred through molecular collisions.

In this Investigation, students will work toward independent experimentation in the context of cellular respiration and photosynthesis through use of a series of physical labs and either CO2 sensors or a semi-quantitative leaf disk protocol. Students will explore changes in CO2 concentration in the context of spinach leaves in light and dark conditions then develop an independent experiment in groups or as a class to reason through timing of cellular respiration and photosynthesis. The scaffolding for experimentation is less than in previous Investigations, leaning on what students have already experienced in the lactase and osmosis experiments.

How do scientists detect planets around distant stars? Use this model to explore how a star's movement and light intensity are affected by an orbiting planet. Explore the effects of changing the orbiting angle (tilt), type, and size of the planet on the star's velocity and light intensity. Use the habitability analyzer to determine whether the planet could harbor life.

What do plants eat? This unit explores plants and how they make food.

Explore what happens when a force is exerted on a polymeric plastic material. There are many different types of materials. Each material has a particular molecular structure, which is responsible for the material's mechanical properties. The molecular structure of each material affects how it responds to an applied force at the macroscopic level.

The Plate Tectonics module "What will Earth look like in 500 million years?" helps students build a systems view of plate tectonics through focused case studies and interactions with the Seismic Explorer and Tectonic Explorer models. As students explore data about plate boundaries on Earth today, they make connections to what happened in Earth's past. Finally, they use their understanding of how Earth's plate system exists today to make predictions about what Earth may look like in 500 million years.

Observe how molecules with hydrophilic and hydrophobic regions move in a mixture of oil and water, and the effects on potential energy.

Explore the role of polarity in the strength of intermolecular attractions. While all molecules are attracted to each other, some attractions are stronger than others. Non-polar molecules are attracted through a London dispersion attraction; polar molecules are attracted through both the London dispersion force and the stronger dipole-dipole attraction. The force of attractions between molecules has consequences for their interactions in physical, chemical and biological applications.

Explore how the types of atoms forming a bond affect the distribution of electrons and overall shape of the molecule.

Many factors influence the success and survival rate of a population of living things. Explore several factors that can determine the survival of a population of sheep in this NetLogo model. Start with a model of unlimited grass available to the sheep and watch what happens to the sheep population! Next try to keep the population under control by removing sheep periodically. Change the birthrate, grass regrowth rate, and the amount of energy rabbits get from the grass to keep a stable population.

Explore how hydrophobic and hydrophilic interactions cause proteins to fold into specific shapes. Proteins, made up of amino acids, are used for many different purposes in the cell. The cell is an aqueous (water-filled) environment. Some amino acids have polar (hydrophilic) side chains while others have non-polar (hydrophobic) side chains. The hydrophilic amino acids interact more strongly with water (which is polar) than do the hydrophobic amino acids. The interactions of the amino acids within the aqueous environment result in a specific protein shape.

Generate all hydrophilic (polar), all hydrophobic (non-polar), or random proteins and observe how the protein folds in response to these molecular properties. Explore how the potential energy of the system changes over time to draw conclusions about how proteins develop stable structures.

Given the equation of a quadratic function in vertex form, students learn to identify the vertex of a parabola from the equation, and then graph the parabola. Two different quadratic equations are provided in this activity.

Students solve two problems involving the motion of projectile objects, modeled using quadratic equations. Students graph parabolas and use the graphs to answer questions about projectile objects. Students identify the maximum heights of the moving objects and discover how long each object is in the air before hitting the ground.

Students solve two problems modeled by quadratic equations. One problem involves profits from a business and the other, water draining from a bathtub. Students graph quadratic equations and use their graphs to answer questions.

Delve into a microscopic world working with models that show how electron waves can tunnel through certain types of barriers. Learn about the novel devices and apparatuses that have been invented using this concept. Discover how tunneling makes it possible for computers to run faster and for scientists to look more deeply into the microscopic world.

How does energy flow in and out of our atmosphere? Explore how solar and infrared radiation enters and exits the atmosphere with an interactive model. Control the amounts of carbon dioxide and clouds present in the model and learn how these factors can influence global temperature. Record results using snapshots of the model in the virtual lab notebook where you can annotate your observations.

Observe a reaction between hydrogen and oxygen atoms, and watch how potential and kinetic energy change.

Carefully observe changes in kinetic and potential energy as hydrogen and oxygen molecules react.