Lesson Plan

I've Fallen.......

Subject Area

Science

Grade(s)

5

Overview

In this lesson, which was adapted from Gravity and Falling Objects, students predict what will happen when different objects are dropped at the same time from the same height, and then test their predictions. Next, they will observe objects of different masses being dropped and leaking cups being dropped into a bucket. The activities in this lesson will demonstrate that all objects fall at the same rate, regardless of their mass. Finally, students will predict what will happen when two balls of the same mass but different volumes--and then two balls of different masses but the same volume--are dropped at the same time from the same height.

This lesson results from a collaboration between the Alabama State Department of Education and ASTA.

Science (2015) Grade(s): 5

SC15.5.7

Design and conduct a test to modify the speed of a falling object due to gravity (e.g., constructing a parachute to keep an attached object from breaking).*

Unpacked Content

UP:SC15.5.7

Vocabulary

  • gravity
  • design
  • conduct
  • gravitational force

Knowledge

Students know:
  • The gravitational force exerted by Earth on objects is directed downward towards the center of Earth.
  • How an engineering design process is used to design and conduct a test.
  • The properties (surface area, substance, weight) of different materials used to modify the speed of a falling object will affect the fall.

Skills

Students are able to:
  • Apply scientific ideas to solve design problems.
  • Generate and compare multiple solutions to a problem based on how well they meet the criteria and constraints of the design solution.

Understanding

Students understand that:
  • A device added to a falling object can cause the speed to be modified.

Scientific and Engineering Practices

Constructing Explanations and Designing Solutions

Crosscutting Concepts

Cause and Effect

Primary Learning Objectives

Learning Targets

I will be able to describe gravity as a force that exists between any two objects that have mass.

I will be able to demonstrate that all objects, regardless of their mass, fall to the ground at the same rate.

Procedures/Activities

Before Strategy/Engage

1. Find out students' ideas about gravity. Ask the following:

  • What is gravity?
  • Where is gravity?
  • What does gravity do?

Give students time to explain their ideas. Record their thoughts on the board or on a piece of chart paper, so that you can return to them later.

2. Hold up a hammer and a feather and ask students to predict what would happen if you dropped them simultaneously from the same height: Would they hit the ground at the same time or at different times? Do not drop the objects at this point. Show students the Galileo on the Moon video. After screening it, ask the following:

  • Did you expect the hammer and the feather to land on the surface of the Moon at the same time?
  • Why do you think this happened?

During Strategy/Explore/Explain

3. Try investigating some of these questions about gravity. Ask students to predict what would happen if you dropped a whole apple and half an apple at the same time from the same height: Would they hit the ground at the same time, or would one hit before the other? Why? Have the students record their predictions and explain their thinking. Ask students to share some of their predictions. Then drop the apples. Allow time to discuss the results and for the students to try to explain the factors that produced them. Use this activity as an opportunity to discuss gravity as a force that pulls objects toward Earth.

Note to the Teacher: 
It is very hard to drop objects at exactly the same time so that they hit the floor simultaneously. You may want to practice ahead of time to prevent false results that will only add to students' misconceptions. Also, even if the apples hit the floor at the same time, students may not believe it! Suggest that they listen for the number of sounds they hear - one or two - when the apples hit. Students might need to repeat this investigation many times since it most likely contradicts their preconceptions.

4. Show the Galileo on the Moon video again. Remind students of the predictions they made in step 2 (would the hammer and the feather hit Earth at the same time). Try it. Then ask:

  • Why did the hammer and the feather fall at the same rate on the Moon but not on Earth?

Introduce the idea of air resistance, a force (friction) that opposes any object moving through air. Ask:

  • What role did air resistance play in the rate at which the objects fell?

5. Show the video What Is "Weightlessness"?. This demonstration can be interpreted as the water floating inside the cup, but from Galileo's experiments, we know that the water and cup are falling at the same rate even though their masses are different. Review what happened in the segment, and ask:

  • Were you surprised that the water stopped pouring out of the holes in the cup once the cup started to fall?
  • Can you think of an explanation for this based on your understanding of the way falling objects are affected by gravity?
  • Why do you think the term weightlessness is used in the title of the video? (optional)

6.  Have students try the falling cup activity from step 5 in your classroom. Experiment with a variety of liquids. Ask students to first predict the results. Do they think they will get the same result no matter which liquid is used, or a different result? Ask them to explain their reasoning; see how well they apply what they have learned from previous investigations to these new situations.

Assessment Strategies

Assessment: (Performance)

You are a team of engineers who have been given the challenge to design a parachute out of everyday items. Your challenge is to design a parachute that can carry one metal washer to the ground from a height of 2M and hit a 10 cm target with the slowest possible rate of descent. The parachute that can hit the target with the slowest descent rate is the winner. 

The assessment for this lesson will be a performance assessment.  Students will work in groups for this performance assessment. Please see the link entitled, "Playing with Parachutes": http://tryengineering.org/lesson-plans/playing-parachutes.

Acceleration

Extension/Acceleration

Using the paper material that worked the best, do the same activity testing the parachute size. Have students test circles with different radii to find the optimal size.

Try parachutes with and without holes in the top (and with different-sized holes).

Make parachutes using different materials, such as plastics, cotton and nylon.

Hold a competition to find a design that can land a toy vehicle most gently.

Intervention

Remediation/Intervention

Students who need additional support can view the "Background Essay" included with the "Galileo's Experiment on the Moon."

Approximate Duration

Total Duration

Greater than 120 Minutes

Background and Preparation

Background/Preparation

We often take the force of gravity for granted, even though Earth's gravity is what keeps each of us from floating off into space! In this lesson, students begin to more fully understand and appreciate the force of gravity. They predict what will happen when a whole apple and half an apple are dropped at the same time from the same height then test their predictions. Next, they observe cannonballs of different masses being dropped out of a tower, and leaking cups being dropped into a bucket. These activities demonstrate that all objects fall at the same rate, regardless of their mass - a concept known as the law of falling bodies. Students then watch a video segment showing a NASA astronaut dropping a feather and a hammer on the Moon. They repeat the activity in the classroom then consider why these objects fall at the same rate on the Moon but not on Earth. Finally, they use what they have just learned to predict what will happen when two balls of the same mass but different volumes - and then two balls of different masses but the same volume -- are dropped at the same time from the same height.

Before you begin, you may want to review the following terms. Mass is the amount of matter in a given volume of something. Volume is the amount of space that an object or substance takes up. For example, the mass of a bag of fluffy marshmallows is the same before -- and after -- a stampede of elephants changes its volume by squishing it to the size of a bar of soap. An object's mass is what determines how much force is needed to move, speed up, or slow down the object. The greater the object's mass, the more force it takes to change its motion.

Gravity is the force that exists between any two objects that have mass. Weight is a measure of the force of gravity pulling on an object. Some people think that the mass of an object and its weight are one and the same, probably because we weigh things to determine their mass. But weight and mass are not the same. How much something weighs depends on how strongly gravity is pulling on it. So something will weigh less where the gravitational force on it is weaker (as on the Moon or in space, for example), even though its mass has not changed.

Materials and Resources

Materials and Resources

  • chart paper
  • hammer
  • feather
  • apples
  • knife
  • two balls of same mass, different volumes
  • two balls of same volume, different masses
  • foam cups (optional)
  • various liquids, including water (optional)
  • bucket (optional)

Technology Resources Needed

Galileo on the Moon

What is Weightlessness?

Approved Date

2016-04-26
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