###### Storyline Narrative 6.1.2

SEEd Standard 6.1.2 asks students to develop and use a model to describe the role of gravity and inertia in orbital motions of objects in our solar system.

Students begin this storyline engaging in asking questions about why the planets the orbit the sun. Students will observe the solar system using Universe Sandbox and use the patterns they observe to generate questions that help them answer why planets orbit the sun. Students are left asking the question, what are the forces that keep the planets from floating away?

Students create a model to explain that the planets revolve and stay in an orbital pattern around the sun. Students discuss what forces keep the planets from floating away. Students explore by investigating how gravity is affected by different properties as they adjust mass and distance. Students use this understanding of gravity to develop a model of what is happening in our solar system. Students discover gravity is a force that is increased as mass increases or as the distance decreases. Gravity decreases as mass decreases or as distance increases. This leaves students questioning why the planets don’t get pulled into the sun by gravity.

Students discuss the patterns they see and predict what would happen to the planets when the sun’s gravity is taken away. Students develop their model of the system further as they investigate with a marble and a hoop to explain the phenomena. Students communicate that an object in motion will stay in motion unless acted upon by an outside source, also known as inertia. Students then ask the question, how do planets gain inertia?

Students investigate how magnets, which exhibit similar characteristics as gravity, come together. Students observe that as magnets come together, the system begins to spin. Students elaborate by developing and using a model of the solar system to construct an explanation of how gravity and inertia work together to form systems. Students further their model by using a chain to observe that as matter circulates in space around an axis, it causes the matter to move outward from the center, compressing and forming a disc-like shape. Students observe this pattern on various scales, including sun-planets and planets-moons.

To evaluate student’s proficiency students are assessed on their use of evidence in their constructed explanations of the phenomena.

#### Episode 1

Question

Why do planets orbit the sun?

Snapshot

Students observe the solar system using Universe Sandbox. Students use this observation to generate specific questions to help them answer why planets orbit the sun.

Conceptual Understandings

The planets revolve in an orbital pattern around the sun. Planets stay in the same orbital motion and pattern as they revolve around the sun.

What are the forces that keep planets from floating away?

Conceptual Understandings

Gravity is a force that is increased as mass increases or as the distance decreases. Gravity decreases as mass decreases or as distance increases.

Why is the sun’s gravity not pulling the planets into the sun?

Snapshot

Students discuss gravity and what they understand about the force. They investigate how gravity is affected by different properties as they adjust mass and distance. They use this understanding of gravity to develop a model to describe what is happening in our solar system.

#### Episode 2

Question

What are the forces that keep planets from floating away?

#### Episode 3

Question

Why is the sun’s gravity not pulling the planets into the sun?

Snapshot

To observe the other force that is keeping the planets in orbit, students observe the absence of the sun’s gravity within the solar system using Universe Sandbox. Students discuss the pattern they see and predict what will happen to the planets. Students develop this model further as they use a marble and hoop to help explain this phenomena.

Conceptual Understandings

Newton’s first law, an object in motion stays in motion unless otherwise acted upon. (They don’t necessarily learn the words - Newton’s first law, but understand the process.) This resistance to change is known as inertia.

What keeps planets in orbit?

Conceptual Understandings

The combination of gravity and inertia is what keeps planets in their orbit.

Why do the planets stay in their particular orbit?

Snapshot

Students observe how magnets, which exhibit similar characteristics as gravity, as they come together. Students observe that when magnets come together they begin to spin. Students observe images of interstellar clouds in the universe, taken by the Hubble Space Telescope. They then watch a short video that simulates what happens as matter in these clouds comes together. They use their model to construct an explanation of how gravity and inertia work together to form systems, in particular our solar system.

#### Episode 4

Question

What keeps planets in orbit?

#### Episode 5

Question

Why do the planets stay in their particular orbit?

Snapshot

To develop students model further, students spin a chain to observe how as matter circulates in space around an axis, it moves outward from the center, compressing and forming a disk-like shape. Students look for patterns within our solar system where it seems this trend is followed.

Conceptual Understandings

As matter spins around an axis, matter compresses and spins outward. Causing the matter to become disk-like. We see this pattern in various scales: Sun-planets and Planet-moons.

Can I use my model to describe the role of gravity and inertia in orbital motions of objects in our solar system?