Build an Approximate Scale Model of an Object

Modeling and prototyping is an important part in the engineering design process. Before beginning work on a new project, engineers develop models of what they want the product to look like. Models serve as examples both for those involved in development as well as customers.

After this activity, students should learn:

• What a scale model is and how to construct one
• The uses for scale models and why they are produced

Have you ever built or seen a model car or airplane? They look just like real cars and airplanes, only much, much smaller. These are what you call scale models because they are an exact smaller copy of the real object. Scale models are often built as a hobby, but engineers build scale models as part of the engineering design process when designing objects or structures. There are various ways to define the engineering design process, but all involve the following basic steps:

1. Identify need or problem
2. Research the problem
3. Imagine possible solutions
4. Plan by selecting the most promising solution
5. Create a prototype
6. Test and evaluate the prototype
7. Improve and redesign as needed 

Developing a model (or working prototype) is a crucial step in every definition of the engineering design process. These small-scale models are built to simulate the real larger objects or structures. Experiments are conducted on these prototypes to test how well they work and determine if the design is safe and effective before building the real-sized structure. It is much easier, safer and less expensive to make design corrections on a model rather than the real object.

For example, if an aerospace engineer was in charge of designing a new satellite to orbit Jupiter, she and her team would build a scale model of the satellite and run experiments on the model before building the real satellite. However, if she skipped the design process of building and testing a model and the satellite did not work properly, she would suffer the consequences of wasting millions of dollars of NASA's funding. As an engineer, it is extremely important to understand the significance of creating a scale model.

For today's task, students will act as engineers to develop a scale model using only the materials available and the duration of the class. Successful scale models must show evidence of very careful craftsmanship and the design should be to scale and detailed with proportional dimensions indicated. Teachers can use the Rubric for Performance Assessment (PDF) to assess student work. 

Background

Recommended Resources:

The Wikipedia entry for "scale model" contains several good links to modeling concepts: https://en.wikipedia.org/wiki/Scale_model

Preparation

• Gather building materials.
• Obtain or make a scale model of something the students are be familiar with.
• Have students choose what objects they are going to model. (Tip: You might want to have a few objects for them to pick from; this helps them to choose objects that are not too difficult to accomplish in the time provided. Some ideas include a bridge, skyscraper, car, bus, items around the classrooms, etc.)

With the Students

1. Explain to students what a scale model is. Show the class an example and discuss with the students why they think that engineers would need to make models before making the real things.
2. Ask the students if they know what the engineering design process is. (Elicit student answers). Show the image below or draw the seven steps in the shape of a circle on the board and explain that engineers use the engineering design process to develop new products, processes, and systems around the globe. 
3. Guide students to move into the third  and fourth steps of the engineering design process - imagine possible solutions and plan by selecting a promising solution. Have student teams pick the item or structure that they want to model and sketch out ideas of how to build a scale model. Make sure that they label the different materials they plan to use on each drawing. Once they have several ideas, encourage them to discuss the pros and cons around each idea and select one to prototype.
4. Have students begin the fifth step of the EDP - create a prototype and build their scale models using the building materials provided. 
5. You may choose to have students build something specific, or with a common theme, or have it be open-ended. An easy criterion is to have students build something that is in the classroom, that way, a variety of objects are available and in front of them. Students could also bring objects in from home.

Grading Rubric: Evaluate student models based on the criteria in the attached rubric, including design planning, construction craftsmanship, accurate sketches with proportional dimensions, and demonstrated understanding of the purposes for and value of scale models.

Scaling their Models: Have students measure the height of their models using a ruler. Then ask students how their measurements will change if the models were two, five and ten times bigger.