KerbalEdu Mission Library

Gravity: What makes things fall?

Ages 10-16
Published by TeacherGaming LLC  •  Posted 1719 days ago
Gravity is present everywhere we see. Yet while we instinctively know how it works, it may be difficult to put in words.
Physics - gravity
Average: 5 (1 vote)
Mission Details and Requirements
Created by: MikaelTG
Mission version: 1.0
Supported KerbalEdu Versions: 0.90.0e532, 1.0.2e615
Mission Type: Demonstration, Experiment
Tags: gravity


Additional Material



Introduction: This assignment is designed for primary school physics class. The students are expected to have a grasp of basic mathematical operations (addition, subtraction, multiplication and division). They should have also played KerbalEdu before. Additionally, they should be familiar with accelerating movement. The goal of this lesson is to teach a special case of accelerating movement, gravitation, with missions that are set within KerbalEdu. The inquiry-based challenges are open-ended; there is a goal but the means to achieve it are open. The students will also learn about taking measurements of their surroundings and gain hands-on experience with the concept.


Grade of Student(s): Primary School 3-6, Middle School

Objectives: Students will be able to:

  • Describe gravitation, what causes it, how and why it works differently on different planets

  • Demonstrate understanding of the concepts in KerbalEdu by constructing and controlling vehicles

Timeline: The lesson plan is designed to span a 45-minute lesson but it can be 
used alongside other materials or as a part longer sessions. 

Materials: KerbalEdu installed on the student computers (scenarios Gravity and 
Mun Gravity) and Steps of Inquiry-slide 

Grouping: Students work in pairs or small groups on a computer. If you choose 
to, the first observation activities can be completed with the whole group. Not 
working alone enables different roles for the students and enhances 
collaboration, e.g. one in charge of piloting, one taking measurements and third writing 
down the observations. Also, this creates the necessity to explain theories to your 
partners, making the learning more explicit.​


Learning Activities

Observing  acceleration (Setting up the Context) If you drop an object, e.g. command pod from a height within the atmosphere, what happens to the speed when the object falls and why? We’ll find out in this scenario. 

  1. What happens to its speed when an object falls? Load a scenario called Edu Free Fall (Kerbin) 65 km and tell them to observe its speed as it falls.
  2. Reload and repeat the scenario and ask them what causes the object to fall and accelerate. You can revise the effect of forces on the object’s acceleration based on Newton’s first law: if the object’s speed is changing it is affected by unbalanced forces.
  3. Tell the students to prepare to answer the question as a group or a pair.

TIP: The falling object starts from a hig orbit, if you want to speed up time, you can adjust the warp from top left corner.    

Discussion: Pause the game and round up the answers from each group. If they are struggling to find the cause, you can point to the fact that your course looks like your headed straight to Kerbin, maybe the planet has something to do with this. When you arrive at identifying gravity, you can demonstrate it by loading the Edu Free Fall (Kerbin) 65 km scenario again and telling the students to observe the Force Arrows attached to the command pod. 


Test it Is it true that gravity is constant everywhere? Back your answer with proof! Build a test where you show evidence either way.

You can leave the steps of inquiry -slide on the background.

Before starting experimenting, the students should create working theorems; that is write down how they’ll solve the problem or explain it to their partners to enable critical evaluation. While these conjectures may be very general in nature in the beginning they will deepen over time to more focused hypotheses.  

TIP: For example, the students could build a rocket and thrust straight up. The higher you get, the less thrust you need to maintain your velocity. (Accurately speaking, this approach is flawed since the diminishing drag and amount (weight) of fuel may be perceived as lessening gravity. In order to make this work, the vehicle needs to start from a planet without atmosphere and set infinite fuel on from the cheats menu (Alt-F12).

Gravity on other celestial bodies? Open the next scenario that is set on Mun (Edu Free Fall (Mun) 5 km). What happens to acceleration on Mun? What causes the difference? Link the gravitational pull to the masses of the objects.

Discuss: After experimenting with gravity, the groups will present their hypotheses to the others. This aspect of distributed expertise should be present at all stages of the process: encourage the students to speak to their group and let them know what you’re planning.

Assessment: Assess the activity of the students as collaborators. Did they participate actively as a group member? To make learning more explicit have the students keep logs. As publication is an important part of progressive inquiry, utilize the Flight Recorder tool and accompany the statistics with Mission Reports that explain what happened and why it happened.



Standards Alignment: Next Generation Science Standards (NGGS)



Plan and conduct an investigation to provide evidence of the effects of balanced and unbalanced forces on the motion of an object.


Develop and use a model to describe the role of gravity in the motions within galaxies and the solar system.