July 17th, 2015

In this activity, students work in all dimensions by sketching 2D pictures of trees and designing a series of 3D treehouses that can “fit” in them. Using four different solids (rectangular prisms, cones, spheres and cylinders), students will mine surface area and volume data for each design to see which shaped house works best. Using the mathematical nets in Volumize, students figure out how 2D skins can wrap the 3D shapes that make up their treehouses.

Volumize Activity 5: Treehouse Design

Learning about scale, dimension, mathematical nets, volume and surface area through designing 3D treehouses for a 2D tree.


Expected Activity Time

Treehouse Design (20-40 minutes)

Materials and Prep

  • Treehouse Design student sheets.
  • iPad with Volumize app.
  • Wifi access to send work to other iPads or to the online project space.

Activity Prompt


Intro:Have you wanted your own private hangout with a view from up high? In this activity you will get to design the optimal treehouse hangout and you’ll create four different treehouse designs. Concentrating on basic 3D shapes, you will create a:

  • Treehouse (rectangular prism)
  • Tree Teepee (cone)
  • Tree Pod (sphere)
  • Tree Silo (cylinder)

For each model you will focus on surface area and volume data to help you decide how much material you will need, to determine standing and/or sleeping space inside, and to decipher amounts needed to skin each model so that the covering appears the way you would like on its surfaces. Based on your designs, you will pick the optimal treehouse for you!


To Do

Treehouse Design (20-40 minutes)

Have students open the app and select “Get Building.”

Each student or group needs to start with a sketch of a tree and then take a picture of it. Allow as much or as little time for this as necessary. (Students can sketch their trees at home and bring them in the day of the activity.) Students will then need to set the scale in fairly realistic amounts that allows them to judge if they can stand and sleep in their treehouse.

  • Each treehouse should remain somewhat simple. The first treehouse students design will be a rectangular prism. They may also add a rectangular prism as a roof if they wish.
  • Once the rectangular prism treehouse is designed, students will then draw the skin for it. They can take pictures of drawings and press and hold the shape to Skin.
  • Have students follow their student sheet, adding data to tables as prompted.
  • Repeat the process for the next three treehouses: Tree teepee (cone), Tree Pod (sphere), Tree Silo (cylinder), answering questions and filling in data tables for each.
  • Engage the class in discussion about how their treehouses compare and contrast.
  • Share some of your students’ work.


Building with 3D shapes on top of a 2D sketch that students create is a great way to frame a discussion around the concepts of moving from 2D to 3D. Ask students:

  • What did you notice about the different designs you came up with?
  • What shape(s) seemed to work the best for your needs?
    What did you notice as you tried to skin your treehouses with your sketches?

Extensions and Inquiring Further

Mathematical nets are useful for the skinning done in this activity. One possible extension is for students to create their own nets for their treehouses with paper, cut them out and fold them into shapes. Design an activity called Shape City and have students create a city populated with all the 3D shapes that your class creates. Define the scale so that there is a real world approximation.


Building 3D treehouses on top of a 2D image is a great way to introduce and to talk about the differences between these dimensions. The book Flatland: A Romance of Many Dimensions by Edwin A. Abbott is a story about a world on a two dimensional plane and all the characters that live there. One character gets a new view of reality when it elevates off the plane and gets a view from above. This story is a classic for middle and high school math students. Assigning this novel as a reading would be a great addition to this activity.

Volumize Activity 5: Treehouse Design

For this activity you will be starting with a hand-drawn two dimensional picture of a tree and then, using the Volumize app, you will build a three dimensional treehouse that fits on to the branches. To get started, make a drawing of a tree in the space provided below. Then you’re ready to bring the tree image into Volumize to get building.

To Do:
1. Use your drawing as the background image and set the scale in a realistic way so that you will be able to stand up and sleep inside your treehouse.
2. Create the first model, a treehouse using a rectangular prism. You can also add a rectangular prism as the roof if you wish. Fit the treehouse onto the drawing so that it looks like an actual treehouse. Rotate the model and examine your design from many angles.
3. In the space provided, draw the skin for your treehouse. What would you like to appear on each of the surfaces? Use colored crayons or markers if desired and available.
4. Once you are finished creating the rectangular prism treehouse, your’re ready to move to the next model. Go back to the homepage and create a new project and remember to save each design.
5. Repeat steps 2 and 3, creating each of the following: a tree teepee using a cone, a tree pod using a sphere, and a tree silo using a cylinder.
6. Fill in the data tables and answer the questions about your designs.
7. Be prepared to share your favorite models and engage in a class discussion about the activity.

Volumize Activity 5: Treehouse Design

  1. In the space below, draw a tree leaving a space for the treehouses that you will build in this activity. A small example is shown, but be creative and make a unique tree of your own.
Example tree withspace for treehouse: Your sketch of a tree, with space for treehouse:
  1. The table below is meant to help you keep track of the surface areas and volumes of each treehouse.
Model Inside Height Inside Width Surface Area Volume
Treehouse(Rectangular Prism)
Tree Teepee(Cone)
Tree Pod(Sphere)
Tree Silo(Cylinder)
  1. In the space below, make sketches for the skin of each tree model:
  1. When you added the skins to your tree teepee, tree pod and tee silo, what did you notice about the rounded faces? Did you have to change anything to make sure the skin looked the way you wanted it to?
  1. Did looking at the nets help you in skinning your models? If so, how?
  1. If you were going to fill each treehouse from floor to ceiling with donuts that are 3 inches in diameter and 1 inch thick, approximately how many donuts could you fit in each model?
  1. Assuming you don’t need extra materials for overlapping parts, how much plywood would you need to build each design? Plywood is expensive, what could you change in your design to cut costs for each model?

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Big Idea

This activity builds from 1D to 2D to 3D, incorporating mathematical nets, surface area and volume along the way. Inspired in part by Flatland: A Romance of Many Dimensions by Edwin A. Abbott, in which characters in a two-dimensional world learn about the third dimension, students scale in one dimension, sketch in two dimensions, and work with basic solids in three dimensions. Challenged to build four differently shaped treehouses out of a rectangular prism, a cylinder, a sphere and a cone, students explore the surface area and volume data to determine how much material is needed to cover their house (surface area), how many people can fit inside standing and/or sleeping, and how much stuff will fit inside of each house (volume).

Learning Objectives

  • Students will learn about relationships between 1D, 2D and 3D.
  • Students will understand surface area and volume for rectangular prisms, cylinders, spheres and cones.
  • Students will understand how mathematical nets are related to the 3D objects that they fold into, and how the nets help understand total surface area.

Standards Addressed

Common Core State Standards-Math 


6.G.A.1                 HSG.GMD.A.3

6.G.A.2                 HSG.MG.A.1






Common Core State Standards-Math

Mathematical practices.

MP2: Reason abstractly and quantitatively.

Students create a dance visually and then have to determine the quantitative moves before making it virtual.

MP4: Model with mathematics.

Students outline their dance using the angles of rotation and coordinate notation for the translation.


  • Scale
  • Mathematical Nets
  • Length
  • Surface Area
  • Volume
  • Dimension, 2D and 3D
  • Rectangular Prism
  • Cone
  • Sphere
  • Cylinder

Device Strategies

Single-device implementation

Everyone in the class can create their own drawings of trees and vote on which ones to use. Since there will be four treehouses, use one drawing for each model. Follow the lesson defined below as a class, giving student volunteers turns on the iPad to create models. Project the iPad to the front of the classroom and have students fill out their own data sheets as the class works together on the projects. Discuss as a class observations about dimensions, surface area and volume for each of the treehouse designs displayed.


Multiple-device implementation

If one iPad per student is not possible, groups of two, three or four students per iPad will work just as well. Be sure to ask the students to share tasks in the activity. Each student or group can create their own tree drawings and treehouses following the lesson as defined below.

Tips & Ideas

Getting a handle on orienting the 3D models in the app can be tricky. Here are some helpful techniques:- Tap the lock icon on the bottom left of the modeling screen to enable rotating the base shape (that's the first shape you add to the scene).- Moving your model on one axis often helps maneuver it into its desired orientation.- Try swiping up or down, or right or left, and watch how your swiping affects the orientation.- Zoom in and out on models can help to orient the scene to your liking.- Double tap at any point will return your model to the starting position. This can be very helpful for making modifications to your construction.As you skin your treehouse(s) with your drawings, you may notice that your photos (of your drawing) appear in an orientation you did not expect. Students may need to experiment by changing the orientation that the photo is taken in.