Grades: 9-10
Author: Rodney Rowell ((Lesson based on ideas of Darrell Woods and John Grabowskil)
Source: Rules for Marbles, Marble Experiment
Using the game of marbles, students will explore how momentum is transferred from one object to another object in an elastic collision. Students will determine the properties that make a good shooter.
What should students know as a result of this lesson?
What should the students be able to do as a result of this lesson?
Marbles of many different sizes (mibs and shooters)
Other small balls of high mass (large ball bearings)
Other small balls of low mass (wooden balls)
Other small balls made of different polymers
Basketball or Soccer ball
Tennis Ball
Momentum balls
Copy paper
Transparent tape and masking tape.
Pencils
Hole punch
Wooden rulers with grove down the center
Engagement
Divide the students in to groups of four or an appropriate size for your class. Tell them that they are going to play a game that was very popular when their grandparents or great grandparents were growing up. The students will play the game of marbles with some small changes to the original rules.
Each student should receive seven small marbles (mibs) but no shooter.Students should make a mark on the seventh mib to indicate who it belongs to. (This mibe will be used as the shooter for now.)
Each group should tape a 50 to 70 cm circle on the floor and place six of their mibs in the circle.The game begins by one player knuckling down at the edge of the circle and flicking their mib (shooter). The object is to knock out one or more of the mibs, without the player's shooter leaving the circle. If, the player has been successful, then the player can shoot again from the place where the shooter rested. If, after the player has missed and his/her shooter end up outside the circle, then the player must leave the shooter inside the circle.
The next player takes a turn. Each mib that was knocked out counts for one point. A player may also knock out any other player's shooter that remains in the circle. The game continues until all of the original mibs have been knocked out. The player with the most points wins. In some versions the marbles knocked out of the circle are kept by the shooter. This is sometimes called "keepsies".
Terms: Knuckling down: A player must have at least one knuckle touching the ground while flicking. Fudging: A players hand was lifted off of the ground while shooting. A player will lose their turn for doing so. Flicking: While knuckling down the shooter is flicked by the thumb out of the players hand. Shooter: The marble that the player flicks toward the target mibs. The shooter must be more than 1/2" in diameter, but not over 3/4" in diameter. Mib: One of seven 5/8" marbles placed in the center of the circle.
Allow the students to play and then have them write a paragraph describing what they saw. Check for use of vocabulary and other observation concerning the collisions between the marbles.
Tell the students that they will use science to find a way to "cheat" in marbles. The goal is for the students to find that the heavier the shooter, the more momentum it has and the more marbles it can knock out of the circle, i.e. the conservation of momentum.
Instructions for playing marbles came from the referenced website.
Exploration
Part 1
| Trial | Number of mibs in tube | Number of mibs on ruler | Number of mibs sent off the ruler |
| 1 | |||
| 2 | |||
| 3 | |||
| etc |
Part 2
| Shooter | |||
| Trial | Number of mibs in tube | Number of mibs on ruler | Number of mibs sent off the ruler |
| 1 | |||
| 2 | |||
| 3 | |||
| etc | |||
Part 3
| Ball Bearings | |||
| Trial | Number of mibs in tube | Number of mibs on ruler | Number of mibs sent off the ruler |
| 1 | |||
| 2 | |||
| 3 | |||
| etc | |||
| Wooden Ball | |||
| Trial | Number of mibs in tube | Number of mibs on ruler | Number of mibs sent off the ruler |
| 1 | |||
| 2 | |||
| 3 | |||
| etc | |||
Students should repeat this procedure for different types of balls.NOTE: I did not have time to try Part II of this activity. Six mibs on the ruler is just a guess. The teacher may want to try this part to determine the best number of mibs to begin with.The teacher should monitor the students and make sure they are writing down the data.A more extensive procedure can be found at the referenced website.
Explanation
Have the students discuss with each other how rolling small marbles into small marbles, rolling small marbles into large marbles, rolling small marbles into ball bearings, and rolling small marbles into wooden balls were all different or alike with each other.
Students should write their answers in a paragraph. Students should be able to see the heavier the object, the more small marbles it took to move it.
Elaboration
Discuss with students that momentum is mass times velocity. A train has a huge mass, but even at low speeds it takes a long time to stop because it has a large momentum. A bullet has a low mass but a large velocity and therefore a large momentum.
Using momentum balls, demonstrate conservation of momentum. Swing one, then two, then three balls.
Have the student discuss the results of the exploration/explanation in terms of momentum and conservation of momentum.
Have the students determine which of the balls would make the best shooter and why?
Each group should prepare data tables or graphs to share with the class to support their decision on which type of ball makes the best shooter. A written report should also be developed.
Evaluation
Teacher demonstrationHold a tennis ball on top of a basketball and drop them at the same time. When the basketball hits the floor it will collide with the tennis ball and the tennis ball will move a way with a great velocity. Have the students write a paragraph on what is happening in terms of the conservation of momentum.
Collecting data for the basketball/tennis ball demonstration is tricky, but can be done. According to the formula d=(1/2)gt2 , it will take about 0.45 s for a ball at one meter to fall to the floor. According to the formula V=2gt, the velocity of the ball at the time of impact is 4.43 m/s. The momentum of a ball falling from a height of one meter is the (mass)(4.43 m/s). It is very hard to measure this small amount of time accurately with a stop watch.
Tape paper from the top of a wall in your classroom to the floor and mark of increments of 10 cm. Using a video camera, tape the dropping of the balls. In a four head VCR, each frame represents 1/30th of a second (or it takes 30 frames to make one second of time). Play the tape back in slow motion and count the number of slides it takes for the ball to hit the floor and then divide by 30. (The ball should take about 15 slide to fall.) This will give you the approximate fall time. The velocity and momentum can be calculated with the aforementioned equation.
Tape the basket ball drop and determine time of fall, velocity and momentum.Tape the tennis ball drop and determine the time of fall, velocity, and momentum. Tape the basketball/tennis ball drop determine the time of fall, velocity and final momentum of the tennis ball. The final momentum of the tennis ball should be approximately the sum of the individual momentum of the basket ball and the tennis ball.
Demonstration
Demonstrations are presented in the Elaboration portion of the learning cycle.
Direct Instruction
Direct instruction takes place in the Elaboration portion of the learning cycle.
Cooperative Learning
Cooperative learning takes place in the Engagement and Exploration portions of the learning cycle.
Skills - Students should be able to define and describe velocity and mass of an object.Students should be able to collect and organize data from an experiment.
Goals - Students should be able to compare the momentum of two different objects.Students should be able to describe how momentum is conserved in an elastic collision.
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