For the activity, each group of 2-3 students will need about half a stick of modeling clay. Each table (testing station) will need one plastic tub that can hold about 6 inches of water, 100+ washers, 1 roll of paper towels, newspaper (to cover the work surface).
I start this lesson by presenting the NASA video "Intro to Engineering", and hold a brief discussion centered around the question, "What is the difference between science and engineering?"
After we watch the video, we have a brief conversation that centers around the difference between science and engineering. The point I want the students to take away from this introduction is that science explains why something happens whereas engineering solves problems (often applying science concepts).
I tell the students that today they will answer one question: "How do engineers come up with solutions to a problem?" In order to answer this question, they will work in a partnership or triad to solve an engineering design challenge. As they are working on the challenge, they must record every detail of what they are doing in order to answer today's question.
To get the point across about the need to record everything, I say, "Go ahead, get to work", and wait until someone asks, "What is the design challenge?" To which I answer, "Oh, so your first step was to define the problem", and write it on the board.
"Define the problem: Design an object out of clay that can carry a load of at least 15 grams."
I ask, "What do I need to know now? I already know that the object must be made out of clay, and carry a load of 20 grams. What other rules might we need?" As I am showing this think-aloud, I write on the board, and integrate their ideas (Practice 1: Define constraints and specifications for a solution):
"Define specifications and constraints: made out of clay, carry at least 15 grams, float." Here, it is important to let students know that wet clay might become unusable, so they must dry it between tests using paper towels.
I continue by asking, "Now what?"
"Create data table: Draw our first idea, build it and test it to see if it can carry the load requested."
Now we are ready to get to work. I have one student from each table pick up a tub that contains the materials, and clarify that they are working in pairs or triads, so the tub contains two pieces of clay (one for each mini-group), but only one tub with water, newspapers to cover the table and several weights.
As the students work, I am circulating the room encouraging the partnerships to make improvements every time their boat sinks, and making sure that each iteration is recorded. (Practice 6: Constructing explanations (for science) and designing solutions (for engineering) - specifically, "Optimize performance of a design by prioritizing criteria, making trade-offs, testing, revising, and re-testing.")
After 30 minutes of building and testing, I tell the students that they will now present their work. One student will present a diagram or flow chart of the steps they took to solve the challenge and the other(s) will present their most successful design - this means they must show it to the class (in some cases re-build it using dry clay), tell what was the maximum load it carried, and "prove it". (Practice 8: Obtaining, evaluating, and communicating information.").
Watch as one team presents their boat (which holds 30 grams):
Student work reveals an honest attempt at keeping track of the different trials to meet the requirements. Although I would have liked to see some explanation of the design choices in their work, it is evident that the the students applied the engineering design process as they tested, revised and re-tested in an attempt to optimize the performance of their design (NGSS Engineering Practice 6).
I close this lesson by facilitating a brief discussion around the initial question, "How do engineers solve problems?"
I hand out copies of several examples of the engineering design processes, and ask students to compare them among themselves and to the work they did today.