What’s in This Unit?
Space exploration generates excitement and captures imaginations, while also leading to major breakthroughs in science and technology. However, the rockets used to launch spacecraft are very expensive, and most can only be used one time. To prepare for future large-scale space projects, such as space colonization, scientists must find a cheaper and faster launch system. NASA scientists believe that a promising technology already exists in the form of electromagnetic launch systems, but the technology needs further development. In the role of physicists working for the Universal Space Agency, a fictional agency that resembles NASA, students investigate the unexpected results from one test launch of a magnetic spacecraft. While scientists at the USA were testing the launch system, they found that the spacecraft in their third test traveled much faster than expected, and it's this unexpected outcome that serves as the anchor phenomenon for student investigations in the unit. Was there an error in magnet alignment? Was there an unexpected energy increase in the launcher system, or was there more magnetic force? Motivated to understand what affects the movement of magnets, students use the Magnetic Fields Simulation, hands-on activities, and evidence from science articles to learn about magnetic force. Student gain an understanding of how magnetic force causes motion and the relationship of magnetic force to kinetic and potential energy. Students use this newfound understanding, as well as evidence about the spacecraft test launches, to explain what they think happened in the third test. They then apply their knowledge to analyzing three designs for a magnetic roller coaster launcher.
We chose the context of a model magnetic launching system for several reasons. First, it allows students to engage with an area of current technology development—magnetic propulsion systems—for roller coasters and high-speed magnetic levitation trains, along with potential advances in propulsion for spacecraft, ships, and elevators. Second, this context provides a compelling reason for students to grapple with abstract concepts such as non-contact forces, magnetic fields, and potential energy. Investigating the magnetic spacecraft launcher motivates students to integrate two previous areas of study: (1) force and motion, and (2) energy. The Magnetic FieldsSimulation allows students to observe potential energy, kinetic energy, and field lines in real time as a system of magnets attracts or repels. Students can then relate changes in force to changes in potential and kinetic energy. Through the Simulation, hands-on activities, and engaging texts in this unit, students develop a broadly useful understanding of the causal relationships between force, potential energy, and kinetic energy.
The Magnetic Fields unit begins by introducing students to a fictional scenario: scientists at the Universal Space Agency can’t explain why their model spacecraft far exceeded the target speed in its third magnetic spacecraft launcher test. To help the USA plan their next text launch, students are challenged to figure out why the spacecraft went so much faster than expected, which is the anchor phenomenon for the unit. To help students explain the unexpected results of the third launch, the problem is broken down into smaller questions.
In Chapter 1, students work to answer the question How can the launcher make the model spacecraft move without touching it? They begin by investigating how magnets move other objects at a distance and then move on to investigating how field lines model magnetic force. By analyzing their data from hands-on activities, the Simulation, and an article about Earth’s geomagnetism, students observe that magnets can attract or repel other magnets based on the orientation of the poles. They also learn that magnetic field lines model attracting and repelling forces.
In Chapter 2, students focus on the question Where did the energy to launch the model spacecraft come from? To investigate how magnets cause objects to have kinetic energy, students first determine how all objects get kinetic energy and then apply it to magnets. Through reading articles about energy transfer in different sports and conducting hands-on investigations, students learn that potential energy converts to kinetic energy. Students then investigate how magnets get potential energy. By running tests in the Simulation, students learn that moving a magnet against a magnetic force transfers energy to the magnetic field.
In Chapter 3, students investigate the question Why was there so much more potential energy stored in the launcher system on Wednesday than on Tuesday? Students investigate what could cause the amount of potential energy in a spacecraft launcher system to vary between tests. By gathering additional evidence from hands-on and Simulation activities, students learn that the strength of magnetic forces affects the amount of potential energy that can be stored in a magnetic field. Students also discover that magnetic force is stronger closer to a magnet. Students use concepts from all three chapters to evaluate evidence about the model spacecraft launch tests and then develop an explanation for the unexpected results in the third test.
In Chapter 4, students apply what they have learned to evaluate competing electromagnetic roller coaster designs by considering the question Which design will launch the roller coaster car the fastest? After evaluating evidence from launch tests based on how well variables were isolated, students retest design variables in the Simulation in order to gather reliable data and apply that data to analyzing three design claims. Students then discuss the design claims in a Science Seminar with their peers and write a scientific argument supporting their ideas about which design will launch the roller coaster car the fastest.