How do we stay on the Earth?

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SWBAT describe why and how we are able to stay on the Earth.

Big Idea

The concept of gravity has many components and student are always curious about why we are able to stay "grounded".

Lesson Overview- 5 E Lesson Planning

5 minutes

Unit 3: Gravity

Lesson 2: Why Don't We Fly off the Earth?

5E Lesson Planning:

I plan most of my science lessons using the BSCS 5E Lesson Model: Engage, Explore, Explain, Elaborate, and Evaluate. For a quick overview of the model, take a look at this video.

I use this lesson model because it peaks the students' interest in the beginning during the "Engage" portion and allows for the students to actively participate in the investigations throughout the subsequent steps. The “Evaluate” component of the 5E Lesson Model can be used in many ways by the teacher and by the students.

A great resource for lesson plan frameworks and explanations is the Community Resources for Science. The 5E Lesson Planning Template and 5E Lesson Planning Prompts come from this website. 

Unit Overview:

In this Unit students will do some investigations about gravity. They will learn about how the planets stay in orbit around the Sun and will re-create Galileo’s pendulum experiments. They will also learn about Sir Isaac Newton’s work and his Laws of Motion as they relate to the idea of gravity.

Lesson Overview:

In this lesson, students will do a simple investigation re-creating Galileo’s work with dropping objects from a height and seeing how fast they fall. I will introduce the terms gravity, gravitational attraction and mass. 

Materials needed:

  • wiffle ball
  • tennis ball
  • ping pong ball
  • golf ball
  • paper
  • aluminum foil
  • cardboard
  • other small objects that are similar in size and shape but have different masses

Next Generation Science Standards:

The NGSS standards that will be covered in this unit/ lesson are:

5-PS2-1. Support an argument that the gravitational force exerted by Earth on objects is directed down.

Disciplinary Core Ideas:  This lesson aligns to the Disciplinary Core Ideas of PS2.B: Types of Interactions  The gravitational force of Earth acting on an object near Earth’s surface pulls that object toward the planet’s center. (5-PS2-1)

Crosscutting Concepts:

Cause and Effect:  Cause and effect relationships are routinely identified and used to explain change. (5-PS2-1)

Science & Engineering Practices:

Engaging in Argument from Evidence

Engaging in argument from evidence in 3–5 builds on K– 2 experiences and progresses to critiquing the scientific explanations or solutions proposed by peers by citing relevant evidence about the natural and designed world(s).  Support an argument with evidence, data, or a model. (5PS2-1)


15 minutes

I remind the students about what we learned in the previous lesson about Galileo Galilei and that we will be re-creating one of his experiments that was shown in the video. 

I start by showing them the wiffle ball that I used in the last lesson as well as a tennis ball. I ask them to write some observations about the 2 balls in their Science Notebooks for a minute (a quick write).

I then have them create a Venn Diagram to compare and contrast the 2 balls. The groups share their Venn Diagrams with each other doing a "Round Robin" and I then do a cooperative learning strategy called "One Stray". One student from each group stands (I pick a number between 1 and 4 since each group has 4 students). The other students remain seated and raise their hands. The student who stands moves to another group when I say "Stray". The seated students encourage the "stray" student to come over to their table and as soon as the "stray" student gets there, the others put their hands down. The new groups share their Venn Diagrams with each other to compare the 2 objects. This is a strategy from Kagan Cooperative Learning Strategies

After a minute or 2 of sharing, I have the students share with the group some things they noticed about the tennis ball and wiffle ball. I am hoping that they come up with the fact that although they are the same shape and size, they have different weights or masses (one is heavier than the other). 

I then ask them to make a prediction of what would happen if I dropped them from above my head at the same time. I tell them to do a "Timed-Pair-Share" with their shoulder partner using the sentence frame of "I predict that____________ because__________" and they write their predictions in their Science Notebooks.  This "Timed-Pair- Share" is also from the Kagan Cooperative Learning Strategies.

After they finish writing their prediction, I hold both balls up (one in each hand) at the same height and drop them.  I repeat this a few times and I have the students tell me what happened. They should be noticing that both balls landed on the ground at the same time.

I ask them to think about why this is happening while they try this on their own with some other objects we have. The objects include a soccer ball, a basketball, a beach ball, ping pong ball, golf ball, aluminum foil (crumpled into a ball), and a piece of paper (crumpled into a ball). I chose objects that would be similar in size but have different masses and weights.




Explore/ Explain/Elaborate

30 minutes

I divide the class into 2 larger groups to work on some explorations of Galileo's experiments. One group will be testing out the demonstration I did with other materials while the second group will be practicing some of Galileo's experiments on the computers. I give each group 10 minutes to complete the investigations.

Object Dropping:

I explain to all of the students before we start the 2 investigations that they needs to follow our Champs for conducting the investigation. I tell them that the objects we are using are tools and not toys and that the balls are only to be used for dropping and not for kicking, throwing or bouncing during science. They also work in partnerships to complete the dropping of the objects. The objects they use are The objects include a soccer ball, a basketball, a beach ball, ping pong ball, golf ball, aluminum foil (crumpled into a ball), and a piece of paper (crumpled into a ball). After a few minutes of dropping these objects,  the students ask if they can try dropping other similar items like pens, pencils, markers, books, rulers. After dropping several items that are similar, they realize that the objects that are similar all land at the same time. I remind the students that they need to drop the objects from the same height and if the want to stand on a chair, they needed to be safe by having someone hold the chair steady when someone stands on it. I tell the students to observe what is happening with the objects and after doing a few drops, to write their observations in their notebooks. I also explain that they need to make sure to drop the items from the same height and I suggest that the students use a meter stick to help them with this. Here's students Dropping Objects and Dropping Objects 2.

Online Investigations: 

I also remind them that the computers are only to be used on the site that I have bookmarked for the investigations. I have the students work in partnerships to share the computers. I tell the students that I want them to practice some of Galileo's experiments on the computer by using this link. I tell them to try to complete as many of the experiments as they can (there are 4) but to start with the "Falling Objects" and "Projectiles" experiments since these are similar to the investigation we are doing. They make predictions of what will happen with the objects before they can click on the demonstration. I tell them to write their observations in their Science Notebooks and any other key words or items that they thought were interesting from the site. This website is great tool to use for explaining Galileo's experiments and how he changed the original thinking about gravity. 

After 20 minutes, I bring the class together to share some thoughts about what they learned. Several students were still surprised that a heavier object and lighter object would land on the ground at the same time. A few students mention that if someone dropped an item that was flat, like a piece of paper or cardboard, at the same time as a round object, that they wouldn't land at the same time. I decide to demonstrate this by using the crumpled piece of paper and a flat piece of paper and ask the students to predict what would happen. Most of them say that the crumpled paper would land first and then I ask them why. A few students determine that the flat piece of paper would be lifted by air and that there is more resistance because there is more surface area than the crumpled paper.

I then show the students this YouTube video to review what we did with the object dropping investigation and to make sure they understood why the objects landed at the same time. i also tell the students that we will be re-creating Galileo's Pendulum Experiments in the next few science classes.