Grade 7 Units

Contact Forces

Oh, no! I’ve dropped my phone! Most of us have experienced the panic of watching our phones slip out of our hands and fall to the floor. We’ve experienced the relief of picking up an undamaged phone and the frustration of the shattered screen. This common experience anchors learning in the Contact Forces unit as students explore a variety of phenomena to figure out, “Why do things sometimes get damaged when they hit each other?”

Student questions about the factors that result in a shattered cell phone screen lead them to investigate what is really happening to any object during a collision. They make their thinking visible with free-body diagrams, mathematical models, and system models to explain the effects of relative forces, mass, speed, and energy in collisions. Students then use what they have learned about collisions to engineer something that will protect a fragile object from damage in a collision. They investigate which materials to use, gather design input from stakeholders to refine the criteria and constraints, develop micro and macro models of how their solution is working, and optimize their solution based on data from investigations. Finally, students apply what they have learned from the investigation and design to a related design problem.

Sound Waves

In this unit, students develop ideas related to how sounds are produced, how they travel through media, and how they affect objects at a distance. Their investigations are motivated by trying to account for a perplexing anchoring phenomenon — a truck is playing loud music in a parking lot and the windows of a building across the parking lot visibly shake in response to the music.

They make observations of sound sources to revisit the K–5 idea that objects vibrate when they make sounds. They figure out that patterns of differences in those vibrations are tied to differences in characteristics of the sounds being made. They gather data on how objects vibrate when making different sounds to characterize how a vibrating object’s motion is tied to the loudness and pitch of the sounds they make. Students also conduct experiments to support the idea that sound needs matter to travel through, and they will use models and simulations to explain how sound travels through matter at the particle level.

Forces at a Distance

This unit launches with a slow-motion video of a speaker as it plays music. In the previous unit, students developed a model of sound. This unit allows students to investigate the cause of a speaker’s vibration in addition to the effect.  Students dissect speakers to explore the inner workings, and engineer homemade cup speakers to manipulate the parts of the speaker. They identify that most speakers have the same parts–a magnet, a coil of wire, and a membrane. 

Students investigate each of these parts to figure out how they use magnetic force to work together in the speaker system. They learn about magnetic fields associated with permanent magnets and electromagnets.  Along the way, students manipulate the components (e.g. changing the distance between magnets, strength of the magnet, number of coils, direction of current) to see how magnetic force can be changed and applied to a variety of contexts, like the speaker, MagLev trains, junkyard magnets, and electric motors.  Finally, students investigate electric force between charged particles to expand their understanding of forces at a distance.

Earth in Space

Humans have always been driven by noticing, recording, and understanding patterns and by trying to figure out how we fit within much larger systems. In this unit, students begin observing the repeating biannual pattern of the Sun setting perfectly aligned between buildings in New York City along particular streets and then try to explain additional patterns in the sky that they and others have observed. Students draw on their own experiences and the stories of family or community members to brainstorm a list of patterns in the sky.  They listen to a series of podcasts highlighting indigenous astronomies from around the world that emphasize how patterns in the sky set the rhythms for their lives, their communities, and all life on Earth.  These are added to their growing list of related phenomena (other patterns in the sky people have observed).

Students develop models for the Earth-Sun and Earth-Sun-Moon systems that explain some of the patterns in the sky that they have identified, including seasons, eclipses, and lunar phases. They investigate the role of light in how we see some patterns, like the red color of a lunar eclipse. The unit ends with a series of lessons related to planets and other objects farther out in space (beyond the stars they can see with the unaided eye).  Students bring their understanding of forces at a distance to this part of the unit, as they investigate the role of gravity in the universe.

Cells and Systems

This unit launches with students hearing about an injury that happened to a middle school student that caused him to need stitches, pins, and a cast. They analyze doctor reports and develop an initial model for what is going on in our body when it heals. Students investigate what the different parts of our body are made of, from the macro scale to the micro scale. They figure out parts of our body are made of cells and that these cells work together for our body to function.

Once students have figured out what their bodies are made of and how the parts of their body work together to be able to move, they wonder how the parts of our body heal. They start by watching a timelapse of a knee scrape and notice that over time the part that was scraped is filled in with new skin cells. Students investigate what happens when cells make more cells, what cells need to make more cells, and how cells get what they need to make more cells. Students return to the healing timeline they made at the start of the unit and apply what they have figured out about the interactions between the different systems in the body to explain the various events of healing that took place for the injury at the start of the unit. Finally, they apply their model for healing to explain growth at growth plates in children's bodies as they become adults.

Genetics

This unit on genetics starts out with students noticing and wondering about photos of the same species of animal with significantly different traits.  The students then observe other animals with similar differences. After developing initial models for the possible causes of these differences ina given trait, students explore a collection of photos showing a range of visible differences among animals and plants.

Students work with pedigrees, including data about chromosomes and proteins, to figure out genetic factors that influence the different phenotype and explore selective breeding in certain animals. In the second lesson set, students use what they’ve learned to help them explain other trait variations they’ve seen. They investigate plant reproduction, including selective breeding and asexual reproduction (in plants and other organisms) and other examples of traits that are influenced by genetic and environmental factors. Students figure out that environmental and genetic factors together play a role in the differences we see among living things.