Lesson Plan – Straw Bridge Design Challenge

Grade Level Gr 4 and up Topics Covered Straw Bridge Design Challenge

Objectives General:

Students will work in teams to design and build a bridge using plastic straws and tape. (masking or scotch) The models will be tested by adding weight to them until they collapse.

Grade-Specific Prescribed Learning Outcomes (BC Curriculum):

SCIENCE: Processes of Science

Grade 4: Make predictions, supported by reason and relevant to the content (Designing a bridge and predicting how it would do)

Grade 5: Identify variables that can be changed in an experiment (Changing the shapes used to build the bridge, number of straws used, length of straws)

Grade 6: Apply solutions to a technical problem (How would you improve on your bridge design? What geometric shapes could you use?)

Grade 7: Create models that help to explain scientific concepts and hypotheses (Designing blueprint, making predictions, testing those predictions, reflecting on how we learn from mistakes/failures)

MATH: Measurement and 3-D Objects and 2-D Shapes

Grade 4: Describe and construct rectangular and triangular shapes (C4)

Grade 5: Describe and provide examples of edges and faces of 3-D objects, and sides of 2-D shapes that are parallel, intersecting, perpendicular, vertical, horizontal (C5)

Grade 6: Construct and compare triangles (C4)

Grade 7: Perform geometric constructions (C3)

SWBAT (students will be able to):

1. Describe and design different types of bridges 2. Identify effective geometric shapes used in bridge design 3. Identify factors that civil engineers consider when

designing bridges Materials 50 plastic straws per team

Tape for each team

Scissors for each team

Handout for each team

Measuring tape/Ruler

2 tables/desks that can be separated 30 cm apart A small paper/plastic cup or container and small objects that can be used as weight. Marbles are a good idea. Each marble can represent 1 car.

Preparation Beforehand

Teacher Contact:

- Use of tables/desks and scissors

- The activity will align with the processes of science section of the

Science IRP

- It would be helpful if the teacher separates the class into groups of 3

befordhand

Activity Preparation: - Gather the above materials and separate them into kits for each team.

Background : Lesson plan was prepared by former civil engineer/now teacher candidate

From the Internet: After the Industrial Revolution, bridges became more and more sophisticated as iron and steel became more commonly available. By using iron and steel, engineers could design bridges capable of supporting larger loads and spanning greater distances, making it possible to link cities and communities through shorter, more direct routes and crossing obstacles such as waterways or other natural features that had previously blocked passage. Sometimes we take it for granted that bridges provide important links between places. They enable us to get to resources, conduct commerce, travel, and visit other people. The design of bridges is important to the transportation networks we depend upon.

Below information can be discussed at any time during the activity. It’s optional and just extra

information. Critical information is embedded into lesson plan.

Connect the fact that while the materials used today will be different. The basic principles such as the geometric shapes used will be the same for our straw bridges as for the bridges we drive over everyday.

Model making is extremely important for engineers. Would engineers build life-sized models of all their designs? (Of course not! Money and time!) Nowadays, most of the modeling is done using computers. The programs used to model bridges and buildings are actually very similar to the programs used to create 3-D animated films. However, sometimes it is still useful to build physical models…and that’s what we will do today!

How much would bridges cost to design and build? A small pedestrian bridge crossing a creek could cost a few thousand dollars. The typical bridges we drive over that cross bodies of water would cost hundreds of millions of dollars. The most expensive ones cost billions of dollars. Port Mann Bridge = $2.46 billion

Pictures and Example Bridge Designs at the end of this lesson plan

Introduction

Objectives Time Instructions Materials

Identify factors that

civil engineers consider

when designing bridges

10 min - Introduce the concept of bridges. Why do we need

them? What are they for? What are some concerns an

engineer may have when designing a bridge? (e.g.

environment, cost, labor, weather, etc.) You could write

down their ideas on the board

-Ask them about bridges in Vancouver so that you are

connecting with the world they know. What bridge

connects ____ and ____? Which bridge will I go over to

get to ______? Which bridge is parallel to ______?

(Linking to their community and math PLO’s)

Draw a picture like the following on the board to help

explain instructions.

-“Today, we will be acting as a team of engineers

making bridge models. We have been asked by the City

of ___________ municipal government to create a

bridge to cross a river. An amusement park is being built

on the other side of the river and visitors need a way to

reach it!”

Design objectives:

You will be given 50 straws and tape and these

are the only materials you can use to create your

model.

N/A

It will have to span the river. The distance our

model will have to span is 30 cm so make sure

the bridge is longer than 30 cm!

The river is the spawning area of many species

of fish. Therefore, we should not disturb this

river. No part of the bridge may touch the

‘water’! This means you can’t have pillars

supporting the bridge in the middle.

You cannot tape your bridge to the desks/tables

to help support it.

To test your design, we will be adding weight to

the bridge until it collapses. That means there

has to be an area in the middle of your bridge

where you can securely hold a small

cup/container. “How many cars can your bridge

hold until it collapses?”

Your design should ‘look’ like a real bridge.

That means you should not just tape a bunch of

straws together into a bundle.

-Reinforce in students that taking risks and making

mistakes are perfectly fine. Engineers do it all the time

when building models and testing. We are not trying to

find a winner in this activity.

Part #1 – Science in Bridge Building Objectives Time Instructions Materials

-Identify effective geometric shapes used in bridge design

15-20 min

Note to Volunteer:

Tensile Strength is the maximum stress that a

material can withstand while being

stretched/pulled before failing/breaking

Compressive Strength is the opposite.

Demonstrate Straw Power: (Optional Extension: This

would be appropriate for higher level classes e.g. grade 7

and up)

1. Have two students come up and try to pull apart a

straw. Discuss “Tensile Strength” if class is at

that level. Otherwise, simply mention it is

difficult to pull a straw apart.

2. Now, cut a short piece of the straw off.

Demonstrate it is very difficult to push it

inwards. Discuss “Compressive Strength” if class

is at that level. Otherwise, simply mention it is

-Straw -Optional: premade 2-D/3-D shapes

harder to crumple the straw if it is shorter. This

concept applies to all materials! Look at the

pillars and columns around your school. The

shorter they are, the harder they would be to

crumple.

3. Ask students to keep these concepts in mind

when designing their bridge. Where would you

want higher tensile strength? Where would you

want higher compressive strength?

Answer: Imagine loading a car on to a bridge.

You would want higher tensile strength at the

bottom of the bridge. You would want higher

compressive strength at the top of the bridge.

Go over Mathematics (Appropriate for all ages)

Ask students what are some 2-D and 3-D shapes they

know. These could be shapes they see in real life or

shapes they have learned in math (connect to their math

geometry unit and math PLO’s) Which shapes would be

better for constructing the bridge? Why?

Lower-level children: Simply use the reason that

some shapes (triangles, arches, X’s, diagonal

beams) would be stronger. They are sturdy.

Higher-level children: These shapes can bear

large loads without deformation. Distribution of

forces: The forces are distributed equally and

transmitted to the base.

Part #2: Design – Blueprint (Pictures at end of lesson plan) Objectives Time Instructions Materials

-Describe and design different types of bridges -Identify effective geometric shapes used in bridge design

10-15 min

-Give handout to students

-Talk briefly about forming their engineering company

and assigning roles to each person. They will need a

president/spokesperson, civil engineer, and project

manager. If they are in groups of 4, they can have more

than 1 engineer or project manager. Have students think

of a name for their company

-Have students sketch a design of their bridge. As a

team, decide on one design they would like to build.

Volunteer should walk around and help guide their

thinking. Do not correct their designs unless it would be

impossible to construct it.

Handouts

Part #3: Building Models (Pictures at end of lesson plan) Objectives Time Instructions Materials

Same as previous

45-60 min

-Handout materials (straws and tape) -Remind them that all students should help with the construction -The main job will be to keep the students on task. Let students know how much time they have remaining. (Write on board and tell them)

- Straws - Tape

Part #4: Testing Models (Pictures at end of lesson plan) Objectives Time Instructions Materials

Same as previous

15-20 min

- Set up tables 30 cm apart - Gather students - IMPORTANT: Reinforce to students that taking risks and

making mistakes are perfectly fine. Engineers do it all the

time when building models and testing. We do this to find

the best possible solution. We can learn from other people’s

models and designs. The results of our tests are definitely

important but all designs, regardless of whether they held

up a lot of cars, will teach us something important. It is not

about which group built the strongest bridge; it is about

learning about building bridges and model making. This is

important because some students will inevitably only see it

as a competition and will become upset if they ‘lose.’ Other

students may brag or make inappropriate comments if they

‘win.’ - The above will be the default strategy. However, some

teachers may want to make it into a competition with a

winning design. Most cars = winner. In some classes, this could work. Please confirm with the teacher.

-Container -Objects to add to container (marbles)

-Have 1 group come up at a time; introduce their companies and why they picked their design, predictions, etc. - Test models! If using marbles, put 5 marbles at a time. Have students count along. You may want to have a student hold their hands under the bridge to catch the container with marbles when it falls. Otherwise, you will have to pick up the marbles after every test. - For some designs without secure spots for the

container, you may have to balance the cup using your

hands. That’s fine. The test is determining when the

bridge will collapse, not when the cup tips over. (Tell

this to the students so they don’t think it’s cheating.)

Note to volunteer: With bridges designed by grade 4’s to

7’s, most bridges held between 20 and 120 marbles.

You may want to set a ‘limit’ where you only test up to

100 marbles. Outstanding designs could take ~200

marbles.

Part #5: Closure Objectives Time Instructions Materials

Review 2-5 min

- After results, ask them some questions. What was

difficult about this challenge? What shapes did you

find useful in designing a bridge? Why were some

shapes better than others? What improvements could

you make after having observed all the tests?

- Praise students on excellent and varied designs.

- Have students clean up all materials/floors (Confirm

with teacher on how they want this to be done)

Pictures:

Designing

Building

Testing

Example Bridge Models

Example Designs Used in Real Bridges