8. Deck The Halls

Students will design a holiday ornament using a 3D modeling program that incorporates at least one example of reflection and one example of rotation.

Depending on the level of the students, there is a Measurement standard that can relate directly to the project.  Feel free to go to the CCSS website and find the one that matched your students the best.

Standards for Mathematical Practice
CCSS.MATH.PRACTICE.MP1: Make sense of problems and persevere in solving them.
CCSS.MATH.PRACTICE.MP2: Reason abstractly and quantitatively.
CCSS.MATH.PRACTICE.MP3: Construct viable arguments and critique the reasoning of others.
CCSS.MATH.PRACTICE.MP4: Model with mathematics.
CCSS.MATH.PRACTICE.MP5: Use appropriate tools strategically.
CCSS.MATH.PRACTICE.MP6: Attend to precision.
CCSS.MATH.PRACTICE.MP7: Look for and make use of structure.

Learning Objectives

  • Students will design a holiday ornament using a 3D modeling program that incorporates at least one example of reflection and one example of rotation.
  • Students will design a holiday ornament that fits into a 90 mm x 80 mm x 10 mm box
  • Students will create a cardboard container for their ornament that is no greater than 90 mm x 80 mm x 10 mm.
  • Students will design an ornament using constructions and transformations prior to designing their 3D products.
  • Students will create an advertisement to promote and market their ornament.


Group Size: 3 to 4 students, depending on how many ornaments you would like to have created and how much time is available.

Class Size: up to 40 students

Materials Required

Assumptions being made:

  • Students have a good understanding of 3D modeling. Prior to incorporating this lesson into a unit, it is recommended that students have had training on Google SketchUp.
  • Students have a good understanding of SAE (Imperial) and/or Metric units.
  • Students have a good understanding of using a ruler.
  • Students have a good understanding of a compass.
  • Students have a good understanding of midpoint and using constructions in geometry.

To begin the lesson, give students an opportunity to discuss their favorite holiday ornaments. If there are students who do not celebrate Christmas, which is highly likely, have them think about a way to encapsulate something they are grateful for within the dimensions provided in the objectives. If students need a visual to play off of, send them to a google search. The theme of the ornament is up to the student (or, if the teacher would prefer, it’s up to the teacher!).

Next, present students with their challenge:

Create a holiday ornament that represents geometric symmetry and transformations.

Using only paper, pencil, a straight edge, and a compass, have students design the 2-dimensional version of their ornament. Encourage the use of a compass and straight-edge for the incorporation of the required symmetry and transformations, while still opening it up to creativity and student choice.

The Meat
Within a 3D modeling program, groups will need to design their layouts for the ornament with the required elements. Because there is likely going to be a lot of extrusion of surfaces within the modeling program, have students do a 360 degree inspection of their own ornament before sending to another group for review.

When printing, it is advisable to print at least 2 perimeter layers thick, so take this into consideration during the design. Each perimeter layer is 0.3 mm thick. Also, since there will be instances during the print in which there is little (or no) support, reduce the speed of the print to allow for more time to cool.

To ensure that everything lines up accurately, groups will check their classmates’ designs prior to showing the instructor. The instructor will need to confirm the students’ designs as best as possible before sending it to print.

Once the design has been printed, students will clean it up and verify all measurements for accuracy with a ruler. Have students paint their ornament if it would add character or meaning to the product.


  • What were some of the challenges in designing the ornaments?
  • What did you learn during the discussion?
  • What would happen if you used a different line of symmetry?
  • After seeing the other groups, what would you do differently?

Each one of these questions can provoke thoughtful responses rich in mathematical reasoning.

Just like in a Research and Design lab for major companies, the feedback and reflection on these projects will be the best part. Give students an opportunity to talk within their group and among their classmates to seek advice on improvements. After completing their print, groups will then proceed to:

  • Photograph their product for their advertisement (if it is a static ad).
  • Reflect on what went well and what they would improve on if they had a chance to print again.
  • Create a marketing plan to sell your product to a specific group of people or industry.
  • Set a desired cost for the ornament, including shipping, based on cost to create the product and cost of shipping.

For the advertisement, students have the option of their medium. Whether it is creating a website, video commercial, radio commercial, magazine ad, billboard, or many others, the key is to be creative in the area that the students are comfortable. During this portion of the project, students will need to work efficiently within a deadline provided by the instructor.

Following the creation, students will showcase their advertisement with the class. If there are local business owners who can come in, this would also be a great addition.

Desired Outcomes
A desired outcome is an ornament that aligns with the appropriate objectives, whether the teacher chooses to maintain the ones suggested here or modifies them to meet the needs of the students in the class.

Some Possible Extensions/Modifications
To scale this down for students who need it, give them a template that holds basic symmetry and have them construct an ornament from that platform

The scale this project up for students who can take it on, require at least one semi-sphere, require all elements to be drawn from scratch (not using any templates), or requiring all alphanumeric designs to be hand-designed.

Once You’re Finished
Your local children’s hospital, retirement community, nursing home, or Salvation Army would be grateful for some handmade 3D printed products. Feel free to get in touch with any of those local entities and reach out to them to show your students’ support of the great work that they are doing.


Content & Instruction Developed by:
John Stevens – Airwolf 3D STEM Consultant
Instructional Coach – Technology
Chaffey Joint Union High School District
CUE Rockstar Faculty & Organizer
Google Certified Teacher
TwitterBlogResourcesAuthor (Flipping 2.0)