How I Introduce 3D Printing in My Classes

For the last five years, I have integrated 3D printing into my classes as part of student learning.  When I started, I only 3D printed with my Honors Geometry classes.  But in recent years, I’ve expanded 3D printing to my Honors Pre-Calculus classes.  (I teach honors classes, but I would do the same projects in non-honors classes.)  One of my most important learnings:  students create better designs if they understand how 3D printing works.

Here’s how I introduce 3D printing to my Honors Geometry classes.  I use a shortened version of this process with my Honors Pre-Calculus classes.  Note that this process has been five years in the making.  If you have never 3D printed with your classes and you have only a few days of class time to give it a try, just do whatever makes most sense for you!

Explore 2D Cross-Sections of 3D Objects

Note:  This is a topic that I explore more deeply in my Honors Geometry classes than with my Honors Pre-Calculus classes.  The explanation below details what I do in Honors Geometry.

This lesson uses Play-Doh and something that we call a “hi-tech cutting device”: a piece of sewing string for cutting through the Play-Doh. Of course, I start the lesson by asking students to create the ground rules for working with Play-Doh in the classroom.  Every year, the first rule students come up with is, “Don’t eat the Play-Doh!”

Students first make a sphere out of Play-Doh, then use their hi-tech cutting device to cut through the sphere, parallel to the base.  I explain the concept of 2D cross section, and we look at its shape. Does the shape of the cross-section change if we cut the sphere perpendicular to its base?  We repeat this with a cone and with a torus.   This takes about one full class period.  Students LOVE working with Play-Doh, but fun takes time.  It also takes time for them to create, cut, and analyze their shapes.

What is 3D printing and where is it used?

I show these short videos to all of my classes before we 3D print. I look for updated videos each year, but these videos work well:

This usually leads to a productive discussion of 3D printing applications in medicine,  food manufacturing, and construction of homes.

What is the Vocabulary of 3D Printing?

I want my students to speak with confidence about 3D printing.  Using the 3D printer at my school, I point out the extruder, nozzle, build plate / print bed, x-axis, y-axis, and z-axis.

I have a few 3D prints that failed during printing, and I display pictures of those prints to discuss these terms: filament, shell, infill, raft, and supports.  I also talk about the difference between PLA and ABS filament and the cost of a typical roll of filament.   I also pass the failed prints around the room so students can explore them more closely.

I show about the first 2 minutes of this video to introduce supports:  3D Printing Using Support Materials – 3D Printing Tech Tips

In my Honors Geometry classes, we do one final activity:  I ask them to draw 2D cross-sections of the top layer of various 3D objects as they would 3D print.  Years ago, I found this fabulous lesson on the Mathematics Assessment Project website.  The lesson asks students to imagine 3D objects filling with water and draw 2D cross-sections of the surface of the water.  I altered this lesson (and some of the images in the exercise) for my 3D printing needs:  I have students draw 2D cross-sections of the objects as if the objects were 3D printing.  I also ask students if the objects would be able to 3D print in the given orientation without supports.  Of course, we bring out the Play-Doh again so students can check their thinking with a “real” object.

What is the Process to 3D Print an Object?

Student don’t always understand that the process to 3D print an object is very different than the process to print a document with a laser printer.  I created this diagram so that we can discuss what software is used for each part of the process and which person (student or teacher) is responsible for each part of the process.

An image that I created for my classes to discuss the 3D printing process.

Student Reflection

I am trying to integrate more student reflection into my classes, and I love using the free website for student reflection.  First, I create a prompt for my students.  As students respond to my prompt, they can add mindset-inspired sentiments such as:  grew my thinking, learned something new, challenged my ideas, or made me think.  After they respond to my prompt, they are able to read and reply to the responses of their classmates using words and reactions such as: I agree, I have a question, moved my thinking, tell me more, etc.

Here is the reflection prompt that I gave my students this year:

grokspot 3dprinting

Introduce The First 3D Printing Project

My student goals for this project in Honors Geometry are:

  • Learn to use Tinkercad to create objects with holes and objects with multiple aligned parts
  • Learn to export objects as STL files and view the file to identify any gaps between parts
  • Determine the best orientation for 3D printing an object
  • Determine whether or not supports are needed
  • Draw 2D cross-sections of their 3D design

This year, to bring a little cross-curricular work from our Outdoor Education Program’s pollinator garden, I asked my students to design a honeycomb from a bee hive with at least 7 chambers for holding honey.  Maybe we can use these designs again later in the year when we reach the topic of hexagons.

More Info

Looking for some tips to make your 3D printed projects run smoothly? Or more info on the 3D printing process?  Check out this article about 3D printing that I wrote for

Happy 3D Printing!


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