# Building a Tipi

Subject: Physical Science/Aerodynamics/Wind Resistance and Structural Shapes

## Integration & Introduction:

This is a multi-part activity on aerodynamics that demonstrates the importance of shape and size on an object’s wind resistance. Students make their own paper models of two different shapes (a box-shaped house and a cone-shaped tipi) to test and compare wind resistance. Using visual-arts activities clearly illustrates to the students the comparative aerodynamics of the differently shaped objects. A narrative on building Native American tipis gives students additional examples of the importance of aerodynamics in design.

## Learner Outcomes:

Students should be able to:
• Understand that the shape of an object affects the way moving air interacts with that object (i.e., the object’s aerodynamics).
• Construct model buildings that test the different aerodynamics of diverse shapes.
• Appreciate that many Native American tribes designed their homes (tipis) to optimize portability and wind resistance.

• .

## Problem/Purpose:

The purpose of this activity set is to give students an introductory understanding of aerodynamics – how the shape of an object and its profile affect the wind resistance of the object. Students make paper models of a box-shaped house and a cone-shaped tipi to test the concept of aerodynamics in the classroom. They also learn about how Native Americans erect their tipis and then discuss the reasons for tipi design/shape.

## Background:

The Native Americans who lived for centuries on the Great Plains of North America needed to move camp frequently – following migrating bison and other food sources, as well as avoiding harsh weather and enemy tribes. The frequency of moves and the distances traveled necessitated household items that were portable, reasonably lightweight, and easily dismantled and packed. Environmental factors, in particular the rough landscape and harsh weather, also influenced the design of native homes. Very strong winds lasting for days are typical phenomena in the regions inhabited by many nomadic tribes like the Blackfeet, the Crow, and the Sioux. In building tipis, both the conic shape and the numerous supporting poles help reduce the wind resistance and increase the strength of these characteristic dwellings.

Aerodynamics refers to stationary objects relative to moving gases such as air currents or moving objects within those gas/air environments. Understanding an object’s particular aerodynamic qualities is critical in designing such items as large buildings, cars, bridges, airplanes and much more. When designing an object, designers must consider characteristics of both the object (e.g., weight, size and shape) and of the environment in which that object will be used (e.g., velocity of local winds). For instance, certain shapes display far more wind resistance than others, making decisions on shape important in architectural and automotive design.

Steps in setting up a tipi

Different tribes have slightly different procedures used to build their tipis. For example, the Crow and Blackfeet tipis have a four-pole base while the Sioux tipi has a three-pole base. The average number of poles in a tipi is 15 poles for the base, two poles for smoke flaps, and one pole for the medicine pole holding the smoke flap ropes. The door of the tipi always faces east.

1. Lay the base poles on the ground with the tips pointing in the same direction. Tie the poles together with one end of a 20-foot rope, tying about ¾ of the way to the tips. This is called the top knot. Leave the remainder of the rope free.

2. Lift the base poles and spread them apart to form a square (or triangle for the Sioux tipi). The rope should hang down in the middle of the base poles. Measure from the center of the tipi (where the rope is hanging) to each pole. Each pole should be the same distance from the center of the tipi. If necessary, move the poles so they are the same distance. Measure from pole to pole around the circle; poles should be spaced equally.

3. Once the base poles are set and arranged, start adding the rest of the base, one pole at a time. Each tribe has their own way of laying the poles in to lock them in place. A common pattern is to place two poles on the east side of the tipi for the door poles. Poles are then placed one at a time between each of the four base poles. The poles are added behind the previously placed pole, moving in a circle around the tipi, until all except one pole are added to the tipi. A space is left for the final pole at the back of the tipi (opposite the door). The final pole goes in the back to lift the tipi cover and is put in place during step number 5.

4. Once all poles are standing in place, the rope hanging down from the top knot is used to tie all of the poles together. This is done by moving the rope between any two poles to the outside of the tipi. The rope is then flipped up towards the top knot and the person holding the rope moves around the outside of the tipi, securing the rope around the top knot. When the end of the rope hangs about 4 feet from the ground, the rope is wrapped around one pole and tied to that pole.

5. The rolled-up tipi cover is laid on the ground. The final long pole is placed on it and the cover is tied to this lift pole. The base of the pole is placed in the proper place in the circle of tipi poles and the tip of the pole is walked up to place it into position, lifting the tipi cover into place too. The cover is then untied from the lift pole and unrolled over the rest of the base poles to meet above the door space at the east side of the tipi.

6. The tipi cover is fastened together at the front of the tipi with lace pins inserted into cuts in the cover above the door.

7. The two smoke poles are placed into pockets at the top of the smoke flaps, making it possible to open or close the smoke flaps as needed.

8. The ropes from the smoke flaps are tied to a medicine pole (which is shorter than the other poles and stands about 8 feet in front of the tipi).

9. A liner usually is tied inside of the tipi, to prevent air drafts from outside and to help the fire smoke exit upwards.

## Materials/Technology:

• Information materials on tipi-building/types of tipis
• Templates for tipi covers
• Toothpicks
• Clay
• Small rubber bands
• Construction paper (enough for two tipi covers and one house/student)
• Scissors
• Drawing pencils, crayons, markers
• Clear tape
• Rulers

## Vocabulary:

1. Star (Ihke) -A hot rotating ball of gas that created its own light.
2. Constellation (Baakkaalaxpitchee) -A pattern of stars in the night sky.
3. Hercules- Bear Above- Baakkaalaxpitchee

## Procedure:

1. Day 1
1. As a class, look at photos of different types of tipis and discuss how those tipis are made and why Native Americans would build their homes in this manner.
2. Have students cover their desks with paper towels.
3. Distribute clay, toothpicks, and rubber bands to students (enough for each student to construct a 3-pole and a 4-pole tipi).
4. Instruct students to make small balls of clay – three for one tipi, four for the other tipi – and insert their toothpicks into the clay balls.
5. Have students use small rubber bands to connect the toothpicks at the top to form the two tipis.
6. Ask students to cut out tipi covers (two/student) from construction paper, using the tipi cover template provided if desired. Students can decorate their tipi covers at this point, using their own designs or following designs in resource materials.
7. Tell students to wrap the paper covers around their toothpick tipis until tight and then secure with tape. Arrange the tipis in a row in the classroom.
2. Day 2
1. Discuss with the class the different shapes that houses can be, referring to the tipis made in the previous procedure. Ask students to describe the shapes of their own homes.
2. Distribute a sheet of construction paper to each student.
3. Have students use rulers to mark 2½ inches from each side of the paper. Fold the paper on the two lines and then open the paper sheet. The results should look like the following:
4. Have students fold their paper in half, across the shorter width of the paper. Open the paper and fold the top edge down to meet the center fold. Fold up the bottom edge to meet the center fold. Results should look like the following:
5. Instruct students to cut slits as indicated by the red lines on the following:
6. Show students a pre-made house and tell them to fold their own houses into a box shape. Fold section A onto section C. Fold Section B to meet the combined section. Do the same on the other side so that you have an open-topped box. Tape the sides together and turn box over (at this point, students can draw windows and doors on their houses, if desired).
7. Have students use double-rolled pieces of tape (two per structure) to attach their box-houses and one of their tipis to the surface of their desks.
8. Ask students to blow hard on both of their structures, from different directions, and compare the different aerodynamics (wind resistance) of the two types of structures.
9. Lead a class discussion on what the students observed.

## Conclusions:

Example:
Various structural shapes react differently in high-wind conditions.

Example:
Native Americans who used tipis as homes often lived in very windy environments typical of the Great Plains region of the United States. This is one reason for the distinctive shape of their tipi dwellings.

## Assessments:

Participation in class discussions

Individual tipi-making activity

Individual house-making activity

Individual aerodynamics experiment (tipi vs. house)

## Extensions:

Research different building shapes and discuss why those particular shapes are used.

Notice the different types of buildings found in your own town or during a family trip.

Use the Internet or other resources to find information on aerodynamics and airplane or spacecraft designs.

Discuss different aspects of automobiles or aircraft that you have seen and how they affect the amount of wind resistance when driving or flying.

## References/Resources:

• www.opi.state.mt.us
• Sarah Jordahl Reeve, Stories from Our Past (Historical Fiction in the Middle School)
• Committee on Indian Affairs, The Tribal Nations of Montana
• Murton McCluskey, Your Guide to Understanding and Enjoying PowWows
• Virginia Driving Hawk Sneve, Dancing Teepees
Author: Victoria Hawk