Catapults Day 2: Creating Orthographic Projections

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SWBAT: Create orthographic projections of their final catapult design.

Big Idea

Having a plan helps students focus on the task at hand. Orthographic projections help students visualize their catapults prior to their construction.


Designing a plan is an important skill in engineering.  Now that students have their 3 ideas from yesterday, they will share their ideas with their peers and create one final catapult design.  This design is be developed into a detailed orthographic projection.

The lesson continues to help students develop understanding of all MS-ETS standards and MS-PS3-5, as well as practices 1 and 2.  

Students will then use this design to build their catapults on days 3 and 4.

Sharing Designs and Learning about Orthographic Projections

25 minutes

Partners will begin class by sharing their ideas with each other.  I usually assign partners, but you can decide how to handle that issue on your own.  

Now that students have information about various catapult designs, they share their sketches from yesterday with their partner. After deliberating, they come up with their best possible solution and turn that design into an orthographic projection.  

Prior to having students complete their orthographic projections, I use Orthographic Projection (website) to demonstrate how one can create a 3D design on a piece of paper. Each group gathers a Chromebook and accesses the site. They then go through the animated explanation of orthographic projections and take notes in their notebooks.

We review the key points from their research and then students begin to finalize their designs, which will be turned into an orthographic projection. I have rulers readily available for this task. In addition, I ask students to identify where they will place their tape and other materials; this helps with material management during the construction process.  This video gives a general overview of orthographic projections.  You may consider having students watch this or you should watch it yourself to help establish an understanding of orthographic projection works.


Creating Orthographic Projections

45 minutes

Now that students have an understanding of orthographic projections and scale, they must make one for their final catapult design. I give students graph paper, rulers and compasses to create their drawings. 

Students must get their designs approved by be prior to constructing their catapults on day 2. Characteristics that I look for include: straight lines, neat handwriting, approximate measurements using the metric system and all 3 dimensions of the orthographic projection. This video highlights many features of orthographic projections that students should include and consider in their own drawings.