Newton's Second: Having A Ball With Motion

Sue Van Kekerix
Minnehaha Elementary School
Two Harbors, MN
Based on an original activity from Loco Motion: Physics Models for the Classroom by Ed Sobey
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Summary

In this activity, students will use a variety of balls to experiment with force and motion using different masses. Students will be challenged to construct a gravity ball launcher, testing the design its ability to produce the greatest distance and/or height. The students will use measurement and observation to make changes and improve their initial design. Students will then demonstrate their design and compare their measurements, mass, and design to that or their classmates. Students will analyze the results as a class.

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Learning Goals

In this activity, students will work to demonstrate an understanding of mass, force, momentum, and motion by creating a gravity ball launcher. Students will use critical thinking skills paired with observation and analysis of data to improve on the initial design. Finally, students will collaborate with classmates to determine the most effective design.

Context for Use

Grade 5
Any size class
Field Exercise
1-2 class periods, depending on length of class periods

Description and Teaching Materials

Prior to beginning this activity, students would have had at least one lesson on Newton's First Law including some lab time to experiment with inertia and would have taught key vocabulary like force, friction, and acceleration following their observations during the lab. Students would then be able to use that experience to make observations for this lab.

1) Students would be given the challenge to build a ball launcher that uses gravity as its driving force. The teacher would demonstrate how a gravity ball launcher works. The concept of the ball launcher will be observed by students who will then share their observations with the class.

2) Students would be provided with materials such as a variety of tennis balls, basketballs, kickballs, soccer balls, ping pong balls, and super balls (which could be brought from home) to use in this lab. Balls that are not air-filled or of soft materials should not be used as they can cause injury and damage (no marbles, golf balls, metal balls, wooden balls, etc.) The students can vary the size of the balls used, but the small ball has to fit inside of the tin can. Students will be given duct tape, tin cans with both ends removed, and measuring tools. Students will collect and record data in their journals. Students will be working in pairs or small groups.

3) Once the teacher is satisfied that students understand their task and the materials to be used, the teacher will describe the setting and rules for the lab area (typically the playground, gym, or other large area with high ceiling clearance). Students will be told to determine their method for measurement of their launches. It is recommended that students use a group member's waist height or shoulder height as a consistent measure of drop height. Students will measure and record the drop height to be used. Remind them to record the units of measurement. Students will create a chart in their journals that looks something like this:

Type of Large Ball Used Type of Small Ball Used Height reached by small ball (units)

Students are also encouraged to sketch their designs each time they change them.

4) Following this task, have students reflect in their journals which combination of balls had the highest launch. They will then take what they determined to be their best launch balls to use in another activity in which they add a third ball. They will create a chart in their journals again, this time resembling this:
Top Ball Type Height (units)

They will again reflect which combination gave them the greatest launch height, as well as making observations about the factors that might have affected how high it launched.

5) Following the activity, students can extend this thinking to try additional balls in their design or modify the initial design to attempt improvement in performance.

6) Students will then meet back in the large group setting to demonstrate and compare results with other classmates. The teacher may want to chart the results from each group as an accountability piece as well as a visual comparison of data. The teacher will ask students what factors may have been factors in the performance differences.

7) Finally, students should write a reflection of their findings in their journal, noting what their understanding was from this activity as well as what questions they may have following this activity.
8) Students need to return their materials to the classroom, being responsible for anything that they used in the field experience.

Teaching Notes and Tips

For safety reasons, the teacher will need to make sure that students are aware of the interference they may be causing by being in the path of another group's launch. Students will also need to be clear on the difference between a drop and a more forceful throw. Dropping means to open your hands and let the ball fall from the pre-determined height. Any other means of moving the ball is not part of this lab experience. Vocabulary in this lesson that might be used include:
Force- a push or pull
Friction-resisting force
Inertia- an object's tendency to keep doing what it's doing
Mass- measure of an object's inertia
Gravity-an acceleration toward earth's center
Acceleration- rate of change in velocity
Velocity-speed in a direction
Some words might come up as a result of other labs, while others might need to added as follow-up to their observations. I have included some words you might encounter, but there might be others as well. The following are resources which I used in preparation for this lesson:
Resources used :
Loco-Motion: Physics Models for the Classroom By Ed Sobey (Gravity Ball Launcher)
Stop Faking It! Finally Understanding Science So You Can Teach It : Force and Motion by William C. Robertson, PhD
This activity is different than activities I have done in the past because students are not directed which specific materials to use but may rather choose their own combinations based on what they predict what will give the best results. They are not told the outcome of their investigation. Students are given the general concept, then are allowed the freedom to redesign the teacher's model. The students are recording their observations in a journal. Students are collaborating in small groups initially; however, in the end, they are comparing their designs to those of other groups.

Before the lesson begins, it might be helpful for students to see how each ball bounces in isolation before creating their design.

Assessment

Students would be assessed on their journal entries. A good journal entry would include a chart of their own design which records the required observations using units of measurements consistently. Students should also have a reflection piece following the lab. A good reflection piece would include their observations of their own designs as well as the design of other groups. The student would also make a concluding statement of their understanding of this activity. Students will be observed for their group skills as well as their individual contributions to the whole class discussion

Standards

5.2.2.1.2 Identify force...
5.2.2.1.3 Demonstrate a greater force can produce greater change in motion.
5.1.3.4.1 Appropriate tools and techniques

References and Resources