• Define a simple design problem reflecting a need or a want that includes specified criteria for success and constraints on materials, time, or cost. (3-5-ETS1-1)
• Plan and carry out fair tests in which variables are controlled and failure points are considered to identify aspects of a model or prototype that can be improved. (3-5-ETS1-3)

• Evaluate competing design solutions using a systematic process to determine how well they meet the criteria and constraints of the problem. (MS-ETS1-2)

• For any pair of interacting objects, the force exerted by the first object on the second object is equal in strength to the force that the second object exerts on the first, but in the opposite direction (Newton's third law). (6-8)

• Possible solutions to a problem are limited by available materials and resources (constraints). The success of a designed solution is determined by considering the desired features of a solution (criteria). Different proposals for solutions can be compared on the basis of how well each one meets the specified criteria for success or how well each takes the constraints into account. (3-5)

• At whatever stage, communicating with peers about proposed solutions is an important part of the design process, and shared ideas can lead to improved designs. (3-5)
• Tests are often designed to identify failure points or difficulties, which suggest the elements of the design that need to be improved. (3-5)
• A solution needs to be tested, and then modified on the basis of the test results in order to improve it. There are systematic processes for evaluating solutions with respect to how well they meet criteria and constraints of a problem. (6-8)
• Models of all kinds are important for testing solutions. (6-8)

• Different solutions need to be tested in order to determine which of them best solves the problem, given the criteria and the constraints. (3-5)
• The iterative process of testing the most promising solutions and modifying what is proposed on the basis of the test results leads to greater refinement and ultimately to an optimal solution. (6-8)

• Models can be used to represent systems and their interactions. (6-8)

• 3-5: 4D/E6. All materials have certain physical properties, such as strength, hardness, flexibility, durability, resistance to water and fire, and ease of conducting heat.

• 9-12: 4F/H4. Whenever one thing exerts a force on another, an equal amount of force is exerted back on it.

• 6-8: 8B/M2. Manufacturing usually involves a series of steps, such as designing a product, obtaining and preparing raw materials, processing the materials mechanically or chemically, and assembling the product. All steps may occur at a single location or may occur at different locations.

• 3-5: 11B/E3. A model of something is similar to, but not exactly like, the thing being modeled. Some models are physically similar to what they are representing, but others are not.
• 9-12: 11B/H5. The behavior of a physical model cannot ever be expected to represent the full-scale phenomenon with complete accuracy, not even in the limited set of characteristics being studied. The inappropriateness of a model may be related to differences between the model and what is being modeled.

• 6-8: 12D/M8. Explain a scientific idea to someone else, checking understanding and responding to questions.
• 6-8: 12D/M9. Prepare a visual presentation to aid in explaining procedures or ideas.

Kids explore civil engineering and architecture as they design and build a small dome frame that can withstand a load of 120 grams on top without collapsing. Editor's Note: For a great 3-day unit that brings in concepts of compression and tension, blend this lesson with the "Teachers' Domain Forces Lab" and the PBS Building Big digital resources in Activities directly below.

• Physical Sciences K-8 Applications of Newton's Laws Unit
• Physics First Applications of Newton's Laws Unit