Make-a-Bite

A 3D printed bite of an animal.

A 3D printed bite of an animal.

A 3D printed bite of an animal.

Learning Objective

For students to explore intermediate 3D modeling such as navigating in 3D space, manipulating primitive shapes to form complex models, and working with measurements and tolerance. Students will experience 3D printing through the lens of a designer creating a functional prototype – in this case, a new animal! This project blends research, presenting skills, and demonstration with technology and design. A strong emphasis on biological adaptation is woven throughout the project.

The final piece is a 3D printed functional animal mouth that will be used for a demonstration showing how the animal survives in their habitat.

Estimated Length

8-10 hours class time + fabrication time

Materials

For each student

• Computer with internet access (1x)
• Computer mouse (1x)

For each class

• Various paints, brushes, markers, paint pens, glue sticks, etc. for decoration. Optional air-drying clay to form heads around the bites.
• Various “diet choices” (clay, paper, plastics, collected leaves & branches, etc.)

Overview of Activity Steps

1. Students discover what can be learned about an animal from their teeth, either through fossils or modern zoology.
2. Students explore different materials that represent different foods. They brainstorm a new animal that would eat a particular diet.
3. Students design their own brand new animal and begin working on a presentation in the style of a new species discovery.
4. Students use TinkerCad, along with a pre-made template model, to 3D design the teeth of their animal.
5. The models are 3D printed.
6. Students test their jaws with their chosen diet. Students can redesign and re-print.
7. Students color their models.
8. Students exhibit the models through their oral presentations and demonstrate how the animal eats their diet.

Setup & Planning

1. If desired, prepare & present relevant classwork. Relevant topics can include: biology & evolution, adaptive traits, fossils & archeology, and zoology.
2. It is a good idea to create a jaw of your own to be able to show the class what they can make! This way, you can demonstrate your jaw consuming a unique diet. Follow the steps to create your own jaw for your new animal!
3. Collect your "diet examples". These can be anything from recyclables (papers, wood scraps, etc.) to live plants/leaves/branches. Organize them in a way that works for your space/classroom. Get creative and choose strange materials such as plastic scraps - what would an animal's teeth need to look like in order to be able to eat plastic? A good stand-in for a carnivore's diet is air-drying clay wrapped in some type of fabric or faux fur.
   • Note: These materials do not need to last the entire project. The students will eventually take what they want to use for their final presentation or you can ask that they bring something from home. Students can even bring in fruit or veggie pieces or eggs for their final presentation and demonstration.
4. It is suggested you create a TinkerCad class in order to streamline the file management process and the 3D printing process. Having a TinkerCad class allows you to look at any student's work from your own account. This can be helpful when checking on progress, fixing small issues, and eventually getting the files for printing. See this official TinkerCad post on how to setup a TinkerCad class. If you do not wish to create a TinkerCad class and activity, you will then need to share the template files with all the students so that they may import it individually into their TinkerCad designs. You may do this via an online file management system (such as Google Drive or Classroom), or by putting it on a thumb drive and downloading it onto each student computer.
   

   Setting up the template files like so can help students envision their final piece.
5. If you create a TinkerCad class, you can upload the jaw template files and add them to “Activities”. Students can then access the template files and import them to their projects. See the below steps:
   1. Click on the TinkerCad class you created. Next, click on “Activities” and then click the “+ New Activity” button to create your stamp activity. Give it a name.
   2. Go back to your homepage and create a new 3D Design on your account by clicking the blue “+ New” button.
   3. Download & import both jaw template files into TinkerCad:
      1. Jaw Template part 1
      2. Jaw Template part 2
   4. Move, rotate, & position the shapes so they look like the photo. The two pieces should be sitting in a sort of simulation to how they will be attached together after being 3D printed. You can also have them flat on the build plate for students to add teeth to, but setting them up like this will be allow them to envision the bite better. Note: the top piece has a semi-circle cutout that the bottom piece fits into. Make sure these are aligned.
   5. Next, lock editing of the template models by clicking the little lock icon in the info panel for each piece. This ensures the students cannot change the size or placement of the template pieces..
   6. Finally, Rename the TinkerCad design name by clicking at the top left where it has assigned a name.
   7. Back on your TinkerCad homepage, click the gear icon at the top right of the design you just made and choose “Add to Class Activity...” and add it to the activity in your TinkerCad class that created.

Procedure

Introduction

Introduce the project

Tell the students that they will be learning about how an animal’s diet relates to its teeth and jaw. Using this new knowledge, they will all be designing the bite of a new animal!

Demonstrate with examples! See some of the ideas below:

• Show/pass around a toothless prototype. You can either have 3D printed out a blank template and loosely wrapped a rubber band around the handle to demonstrate this or you can use a simple folded piece of card stock. This example has weak jaw muscles and no teeth so the bite is not very strong. What kind of things could this animal bite and hold onto? what makes it strong or weak?
• Show/pass around a toothy prototype if you 3D printed one. You can also use a claw hair clip if you did not design and 3D print your own mouth. This example has much more strength in the jaw and it has teeth to help bite onto a surface. Note: If you are using a claw hair clip, you can talk about interlocking teeth. If your 3D printed mouth does not have teeth that interlock, use your fingers to demonstrate the idea. Interlocking teeth can be a challenge to design, but this guide will give tips for that if you eventually have students that want this type of bite.
• Show both examples of your 3D mouth picking up and swinging around items such as felt, paper, larger classroom objects, etc.

Discuss with the students what different teeth and jaws can accomplish in nature. For example:

• Carnivores, omnivores, and herbivores have different teeth from each other. You may want to display or pass around some images of different animal teeth and have the students guess which are which.
• "Some teeth interlock and some do not. and Some simply rest against each other. Some animals, like you, have multiple different types of teeth in your mouth.”
• "Teeth that interlock may make for a bite that can tear while flatter teeth that rest against each other may be better for grinding up food.”

Tell the students that exploring these ideas further in science class, they will design a bite based off a brand new animal they create. They will choose the diet they want their animal to have, sketch the overall look of the animal, 3D design the bite, and then demonstrate how the animal’s bite helps them survive. The students can demonstrate this in any way you want. The bite can demonstrate how it pulls leaves from a branch, how it grinds up food, or even how it might defend itself. Get creative! Let the students know the bites will be printed in white and they can paint them to match their new animal.

Exploration & Brainstorming

The students will now have some hands-on time to examine some materials that mimic some of the properties of different foods. Display whatever diet examples and materials you have collected. Make sure to mention that these are just a few ideas, but they can use other things too. Note that on the day of their presentation, they need to bring their own "diet" from home or ask if they can use one or more of the examples from your exploration bins. You as the teacher can choose not to provide the diets on the day of the presentation. This gives the students a good opportunity to exercise pre-planning skills by making them come up with their own diets.

Today, students will use the 3D printed example bites you created for this exploration. These are general prototypes for students to compare different types of teeth. Student projects will be specific to particular foods and will function better. A prototype is a proof of concept so do not get too focused on the bite working perfectly with the diet materials.

Give the students time to use the example bites to pick up, tear, and mash the different diet examples you brought in. Also, allow them to take notes and even begin sketches of what their bite might look like/what type of animal they will create. You may want to give the students a bit of homework before the design process begins. Ideally they would have initial sketches of the teeth prior to starting in TinkerCad.

Project

The students will now begin designing in TinkerCad!

If you created a TinkerCad class

Below are the steps for students to join your class & pull the template files into their projects:

1. Students should log in to TinkerCAD. Then, have them navigate to “my classes” & “join a class”.

1. Put the class code up on the screen or whiteboard. Students will enter the class code and then they are enrolled.
2. From the TinkerCad homepage, have them click the “Classes” button on the left side under their username.
3. Have them click on the class you created.
4. Have them click on “Activities” and then click the name of the activity you created.
5. There should be a file associated with the activity that they will see which has the template files inside. Have them click on “Copy & Tinker”. This will open up a copy of that design which they can design on! Have the students rename their file with their name to make it easier for you to find later.
   

Explore TinkerCad

Before beginning to create teeth, students should become familiar with the layout, simple tasks, and moving around the workspace.

If you need assistance introducing students to TinkerCad, see our TinkerCad Guide or explore TinkerCad's plethora of interactive tutorials.

Creating Teeth!

1. Have the students access the template files either through your TinkerCad class or by uploading the files manually.
2. Explain to your students what a template file is. Talk about how designers often create and share templates to expediate their prototypes. Talk through the files the students see on their workplane. If you created your own jaw prior to beginning this project, point out each model in TinkerCad and point to its respective 3D printed counterpart. Mention that the template files should be locked and cannot be modified. This is so the students can design their teeth without worrying about accidentally changing the template file's size or shape. If you did not create a TinkerCad class, you will have to instruct the students to lock the models manually.

See some different methods for creating teeth below. You may want to focus on one or two per class period. Remember that further instructions on many of these concepts exist in our TinkerCad Guide.

The process of readying shapes for grouping. In the last photo the Align tool is used to align the two shapes.

• 

  Results of grouping shapes. The right photo shows an additional step where a sphere hole was grouped with the shape to carve it out.
  

  Creating an interesting tooth shape by manipulating the live sketch in the Extrusion shape-generator.
  

  An entire row of teeth is generated with equal spacing using the Duplicate and repeat tool.
  Demonstrate how to make unique teeth by grouping shapes. Encourage students to use more than just a basic shape to create a tooth. Demonstrate dragging out two or more shapes, modifying each shape in some way, and then grouping them together or even making one a hole to group with the other and carve out its shape.
• Demonstrate how to utilize the scribble tool to draw out a tooth shape. This is great for drawing out a unique and naturalistic tooth from a top view. Make sure that the students know they must fill the entire scribble in or else their tooth will have holes in it. The scribble tool can also be used to carve interesting shapes out of a tooth. Simply, create your scribble, turn the scribble into a hole, and group it with a tooth.
• Demonstrate shape generators. Click on “Basic Shapes” and then choose “Shape Generators” to view shape creators! “Extrusion” is a great featured one that can teach kids the basics of curves for 3D modeling. Extrusion (appears as a grey cylinder in the Featured section) can also be used to draw out a tooth from a top view, but in a more controlled way than with the scribble tool. Demonstrate pulling the points and handles of the extrusion drawing and how the shape updates on the workplane.
• Demonstrate using the duplicate & repeat tool. This is a great tool as it can create an entire row of teeth very fast. Then, once the entire row is there, students can go in and carve out scratches and other signs of wear and tear if they want. The duplication & repeat took is different from simply copying and pasting in that you can press the button, then move the tooth next to the original one with the spacing you want. Next, all you have to do is keep clicking the button to keep adding more teeth to the row with the same spacing! Basically, the duplicate & repeat tool duplicated the shape but also repeats any modifications you have made from the original. Have students explore creating a tooth, pressing the duplicate & repeat button, moving the tooth to the size, and then clicking it again!

Outside of TinkerCad:

• For more advanced classes, introduce them to Google Drawing as a tool to create teeth. Using the line & shape tools at the top, students can draw a tooth shape from a top view with even more control than the TinkerCad extrusion tool as they can start from scratch. This can be a tricky method as the shape must be closed in order to be brought into TinkerCad. Feel free to tinker around with this additional tool if desired and demonstrate to your students. When a shape is done, you must download it as a .SVG file and then import it into TinkerCad. Note that the shape will come in at a very large size and will need to be shrunk down.
• For more advanced classes, you may even want to demonstrate sculpt-based modeling as a way to create individual teeth. See our SculptGL guide for some tips and tricks on using this browser-based software to manipulate a digital ball of clay into a 3D model. Note that this method can be difficult for students who haven't worked with 3D modeling before and may involve some file cleanup.

Don't! These teeth will be very difficult to print due to how tall and thin they are. It may be a good idea to print out an example like this to show the students how the printer would handle it. Most likely these teeth will snap very easily or not print at all near the top.

Do! These teeth will print much better because much of the shapes are formed together into a strong base. This base will alleviate the worry of the 3D printer nozzle picking the teeth up while printing and dragging them around. The points also come to a more gradual tip.

The process of creating teeth that will interlock and checking the bite by simulating it with the movement arrow.

The Do's & Don'ts of 3D teeth:

• Avoid creating teeth that are super tiny and/or thin. If teeth need to be sharp, use a gradual slope to a point as opposed to a long and thin tooth.
• Avoid support material by avoiding internal cavities.

Interlocking teeth

Interlocking teeth are easiest to design if the top and bottom row are more or less identical. Of course, once both top and bottom rows are created and fit into the mouth, students can edit small parts of the teeth such as texture, scratches, etc. Students can also attempt making teeth fit into each other using holes. For example, a top row could have cone-shaped teeth that sit into the bottom row by duplicating the top row and turning that copy into a hole. Then you would group that hole row with the bottom teeth. This can get tricky due to 3D printer tolerances, but if students wish to try it, encourage them! They can always redesign.

1. First, you must create one row of teeth in any method of your choosing. The easiest way is to generate a row of triangular shaped teeth with the duplicate & repeat tool. Make sure the row of teeth is situated and sized into the template the way that you want.
2. Next, with the row of teeth grouped together and selected, press the duplicate & repeat button.
3. Use the black vertical positioning cone to move the teeth up and only up - not to the side. Move them all the way up above the top jaw so you can see them.
4. Next, hold shift and rotate the teeth to rotate them around so they are pointing the correct way - they should be pointing down.
5. If you move the teeth down at this point, you will notice they do not interlock, simply move the teeth left or right to position them to fit into the bottom row. Use the left and right arrow keys to ensure you are not moving the teeth back or forward.
6. Now, bring the teeth down slowly with the black vertical positioning cone until they fit into the bottom row. This is checking the fit! If you are happy with the fit, move the teeth up so they are intersecting with the "gums".
7. If there are any teeth hanging off of the sides, remove them by either ungrouping the row and deleting the floating teeth, or by using a hole cube to remove them.
8. Now the teeth should interlock when printed!

Checking the Bite

• After students have made their teeth and positioned them into the jaws, have them use the black arrow to bring the teeth on the top row down to the bottom to check the bite. It may be helpful to group all the top teeth together for this part. Make sure they are looking at where the two rows touch. Is this how they want the teeth to bite? Remember that this project is all about redesigning prototypes so it is perfectly fine if the do not get their bite exactly how they want it the first time. However, checking the bites at this point can really help expedite the students' work. Make sure the students are looking at different angles to check the bite.
• Make sure there are no gaps between pieces of the model. All teeth should be touching either the top or bottom jaw piece. Make sure students are checking this. A good trick to fix floating parts is to create a workplane on the jaw pieces and then press the "D" key while having a tooth selected. This will move the tooth to that workplane so you can ensure there is no gap! This trick only works with certain angles so make sure students are visually checking as well.
• Make sure there the exterior side of each template piece is flat. No teeth should be sticking out through the jaw. We need a flat bottom on the jaw pieces to ensure they sit flat on the 3D printer bed.

This image shows proper rubber band placement on a painted and dry mouth.

Open work time & Redesigning

At this point you are free to structure the in-class working time however you'd like. When students have finished their first designs, 3D print them!

Once the prints are finished, hand them back. Have the students either bring in their own diet materials or put our your collection again. Also set out a variety of rubber bands for kids to test their jaw strength with. Rubber bands can be wrapped around the small groove in the handle. Make sure the prints are totally cooled before allowing students to apply rubber bands. If they are not cooled down, the rubber bands could warp the prints. Also, make sure students are applying rubber bands one at a time. Note that too many could apply too much pressure to the hinge and snap it!

Some students may opt to not use a rubber band at all so they can keep the two pieces separate and use them to demonstrate mashing and grinding instead of biting down and tearing. Encourage students to get creative with their demonstrations!

Have students test their bites! Emphasize that redesigning is encouraged! If a student isn't satisfied with their bite, encourage them to go back to their TinkerCad file and make the changes they want. Then, the second prototype can be printed.

While students are redesigning, they can also work on their slideshows for their "new species discovery" presentations.

Decoration

A student demonstrates their decorated teeth in action!

Once the students have finished designing and printed their final prototype, you can give them time to decorate their jaws! The way they are painted should pertain to how they envision their animal in the wild. Students can explore camouflage to help the animal blend in. Think about inserting some planning skills into this project by having your students make a rough draft of what they want their final piece to look like. Go further by having them list all the paint colors they think they will need. See the tips below for more ways to help your students get their animal jaws looking just right.

• Acrylic paints work best on 3D prints. However, if they are not sealed with some type of clear coating, such as brush-on Modge Podge, the paint can chip if applied too thick.
• Students sometimes can forget which project is theirs. I suggest having a piece of cardboard for each student with their name on it that they can paint on. This way, the pieces can be moved away and stored to dry easily.
• Rubber bands should be removed prior to painting. Have the students store their rubber bands somewhere safe for when the jaws are dry.
• Have students paint one side of each jaw, let them dry overnight if possible, and then do the other side.
• You can provide the students with a lightweight modeling clay if desired. Students can mold eyes, fins, and other details if they wish. I have had students in the past mold an entire body for their animal!

Tips & Tricks

• 

  For exporting each file as an STL, instruct students (or do this part yourself) to copy their mouth and put it somewhere else on the workplane. With this copy, they should group all parts of the top jaw together and all parts of the bottom jaw together and then lay them flat on the workplane.
  For 3D printing, export each student's file in two STL pieces, the top jaw and bottom jaw, separately. This will allow you to move them around and tetris them together to fit more on each 3D printer build plate. You should be able to fit at least four total pieces (or two student projects) on each printer plate.
• Make sure the jaws are printed with the flat side down.
• If you are worried about the redesign process taking a lot of time on the printers and not having enough time or resources for this, think about having each student get a blank template printed. Then, they can simply design and print out teeth/rows of teeth on their own and then glue them into the blank template. This makes it harder to check a bite in TinkerCad, but it does give students some freedom as to where they are placing their teeth. Think about trying it both ways for your own initial example so you can see how long the prints will take and then decide on your plan of action. Note that printing individual teeth can be tricky and rows work much better as most 3D printers do not handle tiny objects very well that are not connected to anything else.
• To make this project more research-based, have your students research a real animal that their new species has evolved from. Have them present on that animal as an intro to their new species discovery presentation and demonstration.

Partnership

This project was developed in partnership with The Avery Coonley School. Special thanks to their wonderful faculty and staff for their continued collaboration.

Additional Resources

Interested in more STEAM Project-based Learning resources? TinkRworks K-8 supplemental curriculum makes it simple to add hands-on STEAM education to your school. Learn more: www.TinkRworks.com.