Heavy vs. Light Falling Objects

Concord Consortium
Type Category
Instructional Materials
This resource, vetted by NSTA curators, is provided to teachers along with suggested modifications to make it more in line with the vision of the NGSS. While not considered to be “fully aligned,” the resources and expert recommendations provide teachers with concrete examples and expert guidance using the EQuIP rubric to adapted existing resources. Read more here.



Students are walked through analyzing data representing  the dropping of a heavy ball and a light ball, making predictions before they see the position vs. time and velocity vs. time graphs for each of these actions. Follow up questions ask about how to interpret the graphs and find the slope and compare the motion graphs for a heavy falling ball and a light falling ball.

Intended Audience

Educational Level
  • High School
Access Restrictions

Free access - The right to view and/or download material without financial, registration, or excessive advertising barriers.

Performance Expectations

HS-PS2-1 Analyze data to support the claim that Newton’s second law of motion describes the mathematical relationship among the net force on a macroscopic object, its mass, and its acceleration.

Clarification Statement: Examples of data could include tables or graphs of position or velocity as a function of time for objects subject to a net unbalanced force, such as a falling object, an object rolling down a ramp, or a moving object being pulled by a constant force.

Assessment Boundary: Assessment is limited to one-dimensional motion and to macroscopic objects moving at non-relativistic speeds.

This resource appears to be designed to build towards this performance expectation, though the resource developer has not explicitly stated so.

Comments about Including the Performance Expectation
The resource analyzes the motion of two objects falling from the leaning tower of Pisa and the position vs. time and velocity vs. time graphs of the two objects are analyzed. The acceleration is calculated from the slope of the velocity graph and the masses are stated but the statement of Newton's second law is implicit in the resource. The acceleration of the ball is proportional to the force acting on the ball, this is an example of Newton’s second law. The activity doesn’t discuss the forces involved directly, but to pull in Newton’s second law the instructor can incorporate a free body diagram of the ball and add a discussion of the forces involved and the changes in magnitude of those force throughout the activity.

Science and Engineering Practices

This resource is explicitly designed to build towards this science and engineering practice.

Comments about Including the Science and Engineering Practice
Real data is analyzed and sources of error and variation from the standard value are discussed. To reinforce this practice, students can be asked to write a reflection on the meaning of each of the graphs they encounter throughout the activity, and on the relationship of one graph to another.

Disciplinary Core Ideas

This resource appears to be designed to build towards this disciplinary core idea, though the resource developer has not explicitly stated so.

Comments about Including the Disciplinary Core Idea
The simulation leads the student through an investigation of the motion of two falling objects of different masses. The relationship to the force of gravity is implied not stated within the activity, although the acceleration of each is calculated by finding the slope of the velocity vs. time graph for each falling ball. This activity can be used in a unit following an introduction to forces and their analysis and perhaps followed by experimentation with falling objects in the lab where they can take measurements of their own to compare to the graphs they saw in the simulation.

Crosscutting Concepts

This resource is explicitly designed to build towards this crosscutting concept.

Comments about Including the Crosscutting Concept
In the activity, the learner examines the difference between a falling heavy ball and a falling lighter ball but in the conclusion see that the graphs have the same acceleration despite the difference in mass of the two balls. This conclusion should be reinforced through either a student reflection with guided questions or a whole group discussion leading the students to this conclusion of the independence of acceleration on mass in this scenario.

Resource Quality

  • Alignment to the Dimensions of the NGSS: The resource directly includes the crosscutting concept, science and engineering practice, and disciplinary core idea.

  • Instructional Supports: The activity is structured so that the student is lead through the exercise from making a prediction and analyzing data from graphs and tables before beginning to writing a conclusion related to that prediction at the end. The student cannot click through the activity without completing the current step. In several parts of the activity, the questions are "responsive" and self-scaffold if a student answers incorrectly.

  • Monitoring Student Progress: The student is prompted for responses throughout the activity and cannot move on until the previous exercise is attempted. The teacher has access to student responses and a record of the student's learning, if the students have an account. A teacher lesson plan, including discussion questions and assessment ideas, is available as a PDF.

  • Quality of Technological Interactivity: The interactive runs well within a browser but you cannot return to a previous screen once you have started the activity.