Water Balloon Toss - Grade 8
Overview
Middle school lessons utilize local phenomenon and are organized by grade bands. By designing instruction around local phenomenon, students are provided with a reason to learn shifting the focus from learning about a disconnected topic to figuring out why or how something happens. #Going 3D with GRC
Lesson - Force and Motion
Student Science Performance
Phenomenon: Sometimes when a person throws a water balloon at me I can catch it without it breaking and sometimes it breaks when I try to catch it.
Gather:
Students explore ways to fill and break balloons in a consistent manner and determine criteria for the problem (e.g., 4-meter underhand toss, drop 2 meters onto grass, drop 1 meter onto concrete) and how to change variables inconsistent ways. Materials – Water Balloons, water, and bins, measuring tape/meter stick, large syringes, and other objects upon request.
Students design a solution to the problem of increasing the proportion of water balloons that survive collisions without breaking.
Students plan and carry out an investigation to test the effectiveness of their solution to the problem of dropping balloons without causing them to break.
Students use a model to organize data from the experiment and find patterns in the data to use as evidence to support an explanation for your solution of successfully dropping balloons without causing them to break.
(Teacher Hint- This activity is definitely an outside activity on a warm day. The focus of this investigation is twofold. One is to help students understand the engineering design - is the figure on the engineering process at the end of the lesson. Students must determine how much water will be added to the balloon. Establish minimum criteria throughout the investigation based upon the strength of balloons. Encourage students to construct a data table to record proportions.)
Reason:
5. Students develop a model to show the system of forces acting on a balloon when it is successfully dropped (without breaking the balloon). (This could be done as a poster.)
Class Discussion:
Q: Why did you select the criteria you did in defining the problem?
Q: How does your model show the forces acting on the balloon?
Q: What causes the balloon to break?
Q: Why is the way the forces are distributed on impact important to the design?
Q: How can we use the laws of motion to make sense of this phenomenon?
Q: What are some examples of analogous phenomena?
(Teacher Hints: It is important students understand that each group is defining the problem and limitations placed on a solution. Focus on the forces, engineering design, and how the design was tested. The laws of motion should be used conceptually not by a number - an object in motion stays in motion - the sum of the forces acting on an object determines the motion of the object - the momentum of an object increases with increasing mass and/or velocity. Analogous phenomena are phenomena with the same causes but the different contexts (e.g., bumpers on cars that have crumple folds to distribute the force of a collision over time, high jump pits have soft landing foam, springs on a car to soften the ride.)
Communicate Reasoning:
6. Students construct an explanation for how the system you have engineered operates to change how the forces acting on the balloons cause fewer balloons to break.
(Teacher Hints: Students focus on both the way the system operates as well as how the design distributes the force of impact over both time and area. Key core ideas for this challenge: 1) an object in motion tends to stay in motion until acted upon by a force, 2) for every force there is an equal and opposite force, and 3) the force is proportional to the mass and velocity of the object.)
*See attached document below for full lesson.
Additional Lessons can be found at #Going 3D with GRC (Gathering, Reasoning and Communicating). Original authors were: Kathy Ulrich, Delene Butler, and H. Guy.