(Also available in WeScheme)
Students define the shapes used to build a rectangular prism, print them, cut them out, and build the rectangular prism. Then they use their model to calculate the surface area.
Lesson Goals 
Students will be able to:

Studentfacing Goals 

Materials 

Preparation 

Key Points For The Facilitator 

 dimension

a measurement of something in a particular direction, especially height, length, or width. The dimensions of a computer screen, for example, are given as width x height.
 face

the flat surfaces on the outside of a solid figure
 rectangular prism

a solid figure which has 6 faces, all of which are rectangular
 surface area

the sum of the areas of all of the faces of a solid figure (polyhedron) or the total area that the surface of the object occupies
🔗Surface Area
Overview
Students build on their experience with writing code to define shapes. They will define shapes for all of the faces of a rectangular prism, print them, cut them out, and build the rectangular prism. Then they will use their model to calculate the surface area and write code to do the same.
Launch

Turn to Surface Area of a Rectangular Prism  Explore. Complete the first two questions.
Invite students to share out to gauge their prior knowledge of surface area.

Now, open the Surface Area of a Rectangular Prism Starter File in a new tab, save a copy, and click "Run".

Type
prism
into the Interactions Area to see an image of a rectangular prism. What do you notice about the prism?
Be sure that students notice that the faces and dimensions (length, width, and height) are labeled. Invite them to observe how many faces there are, as well as how many differently sized faces there are. Students who clearly see that there are three sizes of faces, with two faces in each size, will be able to move more confidently through the remainder of the activity.
Faces are the flat surfaces on the outside of a solid figure. Edges are the line segments where the faces meet in each of the three dimensions. The surface area of a prism is calculated by adding the areas of its faces.

Go to PART 1 and look at the definitions for
front
andback
. Typefront
into the Interactions Area. What do you get?
A blackoutlined rectangle that has a width of 180 and a height of 50.


The faces
front
andback
have been defined to draw a rectangle whose dimensions are width and height. You will need to write definitions for each of the other faces of the prism. 
Click "Run" and test each of the faces in the Interactions Area to make sure that they match the prism you started with.
Facilitation Note
The sample definitions were written to make images of outlined rectangles with a black and white printer in mind. If you have access to a color printer in your classroom, you may want students to change the code of If you do not have a classroom printer, consider splitting this lesson over two days  the Launch segment on Day 1, and the Investigate and Synthesize segments on Day 2. At the end of Day 1, direct students to share their images with you. Print the images and distribute them before beginning the Investigate segment on Day 2. 

Go to PART 2 in the code. Type
printimgs(faces)
into the Interactions Area. How many rectangles do you see?
Two.


The code in PART 2 says
faces = list(front, back)
, which definesfaces
to be a list of values. This list will include all of the faces of the prism, but right now it only includesfront
andback
. Add the names of each of the remaining faces to the list. (Order doesn’t matter  but be sure to put commas in between list items, and do not use the word “and”.)
Ensure that students' lists include all six faces of the rectangular prism.

When you’ve finished, click "Run" and again type
printimgs(faces)
. What do you Notice? What do you Wonder? 
Do you have enough shapes to cover all of the faces of the prism?

Read the comments in PART 3 of the file to learn how to print the faces to build your prism.
Investigate
Have students cut out and tape together the images they defined to form a 3dimensional paper model of a rectangular prism. Students will then use their models to calculate the surface area.
Supporting students with learning variations


Once you’ve built your prism, use it to help you calculate the surface area of the figure.

Then, go to PART 4 in the Surface Area of a Rectangular Prism Starter File and define
surfacearea
using length, width, and height.
Synthesize
Have students share the code they wrote to define surfacearea
. Did students all write the code the same way?
Three possible correct ways to define surface area are:

surfacearea = Afront + Aback + Aleft + Aright + Atop + Abottom

surfacearea = (2 * Afront) + (2 * Aleft) + (2 * Atop)

surfacearea = 2 (Afront + Aleft + Atop)
For further debriefing, discuss the following:

How did building the prism help you to understand surface area?

How did writing the code for surface area help you to understand surface area?
These materials were developed partly through support of the National Science Foundation, (awards 1042210, 1535276, 1648684, and 1738598). Bootstrap by the Bootstrap Community is licensed under a Creative Commons 4.0 Unported License. This license does not grant permission to run training or professional development. Offering training or professional development with materials substantially derived from Bootstrap must be approved in writing by a Bootstrap Director. Permissions beyond the scope of this license, such as to run training, may be available by contacting contact@BootstrapWorld.org.