www.TeachEngineering.org: Free Curriculum for K-12

City planning is the activity of determining the future physical arrangement and condition of a community. This involves examining the present condition, forecasting future requirements, creating a plan to fulfill these requirements, and securing proposals (construction, legal, financial) to implement the plan.

Dr. Seuss' book, The Lorax, has become a popular metaphor when speaking of the impact of human industry on its environment. Building on this story, students learn about city planning and how a variety of types of engineers work together to design and build a new city. Students learn that the fourth law of ecology, "there is no such thing as a free lunch," extends beyond the natural world and into the engineered world. Use this activity as a wrap up of an introduction to engineering and/or an Earth Day activity.

Note about the worksheets: In Part 2, when students are asked to calculate how long it would take to re-build the forest, you have a few options. It is best if student teams are free to brainstorm an approach to solving the problem by themselves, by trial and error, using blank paper. But, if your teams could use some assistance, provide them with Re-Building the Forest Worksheet (A)— a blank table with column headers that serve as clues for how to think the problem through. For younger students, or those who even need more assistance, provide them with Re-Building the Forest Worksheet (B)— a blank table with specific years already in the first column, guiding them through year 42 by which time the forest would have 31 trees.

Gather materials.
(optional; see worksheet note, above) Make copies of the Re-Building the Forest Worksheet, version A or B, one per student.

Read aloud to the class (or show the video of) Dr. Seuss' The Lorax.
Use the following questions to lead a class discussion:

Who is the Lorax? Who does he represent in the real world? (Answer: The Lorax is one of the main characters in the book and he "speaks for the trees." The Lorax represents environmentalists.)
Who is the Once-ler? Who does he represent in the real world? (Answer: The Once-ler is another one of the main characters and he develops an industry selling thneeds. The Once-ler represents industries and factories that are not environmentally friendly.)
Why is the Once-ler called the Once-ler? (Answer: The Once-ler only uses things once.)What is a thneed? Would you want one? Why or why not? (Answer: Students may come up with all of the ways you can use thneeds, as mentioned in the book. Talk about how some products are very useful and we need them, but not without some limitations about how many should be made, etc.)
What happens after the Once-ler sets up his thneed factory? (Answer: The area is slowly destroyed by pollution. All of the animals leave and the once-beautiful truffula forest is left in ruins.)
Where do all the animals go? Why do they leave? (Answer: The animals go off to different places in search of a healthier and safer environment. The pollution from the thneed factory forces them to leave.)
What happens when the last truffula tree is chopped down? (Answer: The thneed factory closes down and the Once-ler's family leaves. The Once-ler finally sees what he has done to the natural area.)

Two photos: (left) A truck carries a load of cut trees on the highway. (right) A hillside looks bare with most of its tall pine trees cut down.

Forests are a valuable natural resource for humans and the natural environment.
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Ask students to imagine that they are the child in the story and have just been given the last truffula seed and a big job to help plant replant the truffula forest.
How long does it take for a healthy forest to grow back? Discuss students' ideas. Ask them to think of ways to prevent the forest from becoming depleted in the first place.
Remind students that engineers are involved in city planning, from designing the buildings and roads, as well as how many and where to place them so as to reduce harmful environmental impacts. Ask students if they think they could design a town in which truffula trees and once-lers and loraxes and they (!) could all live together.

Explain to students that it takes a long time to replant and re-grow a destroyed forest, which is why it is important to help protect our natural resources.
With the students, discuss the last part of The Lorax story — when the Once-ler gives the boy the last truffula seed. (Re-read this section aloud.)
Ask students to suggest how they might go about replanting the truffula forest. How long would it take? (Write students' guesses on the board.) Explain that today they will calculate how long it takes a forest to re-grow.
Give students the following information and ask them to brainstorm in small groups how to calculate the length of time to re-grow a forest of at least 100 adult trees. As adapted from a section in The Lorax video, a single seed takes:

1 year to germinate into a sprout
10 years to grow into a sapling tree
10 more years to grow into an adult tree and produce new seeds
Each tree can produce 10 seeds a year once it reaches maturity

Have teams figure out on their own how to calculate the length of time. Have students choose one method from their group's brainstorming ideas and follow this approach to calculate the number of years. Ask each team to report to the class on the number of years it takes, based on their calculations. (Optional; provide a worksheet, version A or B, to assist students, as necessary; see note on worksheets, above.)
As a class, talk about the different methods and how different groups may have calculated their times. Together, go through an example method (see Figure 1) (or use a worksheet) to ensure all students understand the calculation.

A partial table showing columns for year, # of seeds, # of sprouts, # of saplings, # of mature trees, and data for year 0 with one seed; plus representational data for a few years (1, 20, 21, 47, 48, 49); ending with year 49 with data of 1010 seeds, 4690 sprouts, 100 saplings and 101 mature trees.

Figure 1. Starting with one truffula seed, how long would it take to re-build a forest of at least 100 mature trees? Here's an example approach to figuring it out.
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Discuss with the class the length of time it takes to grow 100 adult trees. If you set the number of trees in a "healthy" forest to be 100 adult trees, it takes 49 years for the forest to grow back. Ask students if they noticed any patterns in the numbers during their calculations.

A drawing shows a building with a door, many windows and three creatively-shaped towers.

A school design for a new town, as drawn by a student.
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Divide the class into groups that represent five different engineering teams involved in city planning. Assign one group to be the commercial team (businesses, shops, hotels, etc.), one group to be the industry team (thneed factories, etc.) one group to be the residential/neighborhoods team (schools, homes, apartments, etc.), one group to be the utilities team (light and power, water, waste) and the last group to be the parks and recreation team.
Have each team come up with a goal for their part of the city planning. For example, the parks and recreation team might want to keep the environment safe and clean to allow for a healthy population of trees and animals, while providing ways for visitors to enjoy the parks. The utility team could focus on renewable energy or clean drinking water. The residential team could focus on having bike paths and sidewalks so that the people can walk safely around town. The industry team might focus on reducing emissions while also obtaining resources such as water for factory production. The commercial team might plan on being centrally located so people can walk to their stores.
After each team comes up with their goal(s), write them on the board and ask students how they might get all of the goals to work together. Explain that sometimes teams of engineers must work together and compromise to reach their goals. Everyone might have to give and take a bit.
As a class, come up with a sketch for a final city plan and zone areas for residential, commercial, industrial, municipal and recreational land use. How will the land be divided up? Draw the plan on the board or mark it up on the felt layout.

Have each team decide a number of things within their focus area that they want to create for the town. For example, the commercial team might draw a movie theater or an arcade. Each team member should draw at least one item that correlates to their specific area. (Additional examples: hospital, drinking water treatment facility, wastewater treatment facility, power plant, recycling center, garbage dump, roads, sidewalks and bike paths.)
Direct the students to draw in Dr. Seuss style. (Have a few Dr. Seuss books on hand as examples, or play The Lorax video, which includes songs, while students work on their drawings.)
In addition to the team drawings, have each student draw their own house or apartment to include in the new town.
Once all drawings are ready, it is time to "build" the town. Ask students to come up to the felt board, one team at a time, to place their buildings, roads, etc., in the appropriate zones. Cut the self-adhesive hook Velcro into small pieces and adhere it to the drawings to make it easy to move items around during discussion and negotiation.

On a blue and green felt background, a collection of hand-drawn images are cut and assembled.

Example completed new town, as designed and drawn by student "engineers."
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After all the drawings are on the board, ask students if they want to make any changes. One way to do this is to make an inventory of the buildings and features of the town and see if anyone thinks of something important that may have been missed in the first brainstorming session. Now is the time to incorporate everyone's suggestions for improvement. This is a great time to talk about just how involved planning can be, and how many different groups and goals must be incorporated to be successful.
Conduct the re-engineering activity in the Assessment section, making comparisons to the engineering design loop. Explain to students that when engineers design, they work in groups and follow the steps of the engineering design process: 1) understand the problem or need, 2) come up with creative ideas, 3) select the most promising idea, 4) communicate and make a plan to describe the idea, 5) create or build a prototype or model of the design, and 6) evaluate what you have made and make improvements (the cycle continues).