We are always looking for new, exciting ways to incorporate standards-aligned projects in the classroom. This week's lesson addresses the steps in the engineering design process. The criteria is to build a container that will keep the egg in one piece when it is dropped from a height. The constraints are the materials and the amount of time given to complete the project.
Although they may not be aware of it, students will complete the steps in the design process. They try various solutions and they decide on one that they use to test their prototype. They test the prototype and in most cases, after the discussion on the science governing the experiment, improve the design and test it again.
Objective: Build a container for an egg that will keep the egg safe (aka in one piece) when it is dropped from a height
Grade levels: 3rd – 8th
- paper towel rolls
- trash bags or plastic bags (for parachutes)
- tissue paper
- egg containers
(Note – You do not need all these materials. This activity can easily be completed with leftover paper products, or other items found around the classroom.)
Procedure: Explain the objective of the lesson. Split students into groups of 4-5. Give them directions on how many materials they can use (set a limit based on quantities available, or set a budget that they cannot exceed and assign costs to each material, or tell them part of the challenge is to use the least amount of materials). Give students time to create their containers. Students come together for the drop and observe how many eggs survived and draw conclusions about why some did and some didn’t survive. Discuss the science behind the experiment (see below). Allow them to redesign and test their egg containers.
Extensions / Adaptation for higher the grade levels: Challenge students to use the least number of materials but keep the egg intact.
The Science Behind it!
Gravity – Force that pulls all objects toward each other and the center of the earth.
Drag – Forces that act in the opposite direction of the motion of an object.
Impact – Force, or shock, that occurs when 2 or more objects collide.
Newton’s Laws of Motion:
An object at rest tends to remain at rest and an object in motion tends to continue moving in a straight-line at constant speed, unless an outside force acts upon it.
Because the egg is at rest, it will not fall unless it is dropped. While it is at rest, it has potential (stored) energy. As you take it further from the ground, it gains more potential energy. When it is dropped, the potential energy changes to kinetic energy (energy of motion).
While it is falling, it is acted on by:
Gravity, which is pulling the egg toward the center of the earth.
Drag, which, depending on how the container was built, is slowing it down.
Impact, which will be determined by how fast it hits the ground and how large the container is.
Force = Mass X acceleration
The container’s acceleration is due to gravity. How much it accelerates, or speeds up, will depend on the height it is dropped from and the mass of the container. The force increases as the mass and / or height increase.
For every action, there is an equal and opposite reaction.
When the egg hits the ground, it will exert a force (impact force) on the ground and the ground will exert the same amount of force (in the opposite direction) on the egg.
Energy cannot be created or destroyed. It can be transferred. The potential energy the egg has while is it raised to a height is converted into kinetic energy as it falls. When it hits the ground, the kinetic energy is stored once again in the egg and its container.
To build the most effective egg container, students are aiming to maximize drag and minimize the impact.
Conclusion: Outline the engineering steps for the students. Do they always follow this order? Not always. For example, in many projects, during the redesign phase engineers might choose to use a new material and will need to do research on that material. Ask students what other projects they have done at school or at home where they have used the engineering design process.