Materials Matter

Students combine paper strips to measure how much gravitational force the paper can withstand by adding masses to the combined paper strips until they tear. Students compare the strength of one paper strip versus the combination of two, three, four, and five strips. Students cut out paper strips and glue them together using a glue stick or a glue bottle. Students punch holes in the paper strips and tie yarn or string through the hole on the paper strip. As they hang the paper strips on the ring stand, they add weights such as a 100 g mass to the paper. When the paper strips tear, the students will record the mass before the paper broke and the mass that caused the tear in the paper. Students will notice that the paper strips tear at increasing masses because of the strength of the combined paper strips.

Students need to understand that composite materials are not created by changing their chemical and physical components. After recording the data, students create a graph with the number of strips on the X-axis and the mass at which the paper tears on the Y-axis. Students compare their findings with the other groups and discuss the results of the project. They discuss why the paper strips could hold more mass as the number of combined paper strips increased. They need to think about what other materials they use in daily life that could be made of composite materials.

Composite materials represent a significant advancement in engineering, offering tailored solutions that address specific needs across various disciplines. Their versatility and enhanced properties make them indispensable in modern engineering applications.

After this activity, students should be able to:

Describe how a composite material can be designed.
Compare and contrast strengths and weaknesses of composite materials and original materials.
Explain how different materials are combined to change their properties.

The backyard of a house with a large deck. Figure 1. Composite materials are useful for building structures such as backyard decks.Copyright EVODEK, 2022, https://www.evodekco.com/how-to-make-beautiful-backyards-ideas-with-composite-decking/

A photo of an electric car made from composite materials. Figure 2. A car with a chassis made of carbon fiber, a composite material stronger than steel.Copyright Nikhil Gupta & Steven Zeltmann, 2016, https://www.livescience.com/53995-carbon-fiber-may-finally-be-coming-to-cars-everywhere.html

(This introduction helps students understand that everything is made of different components that are chemically or physically combined. It also introduces students to how objects such as cars, phones, and roads are built.

Tell students: “Before engineers can solve a problem, they determine the criteria and constraints and conduct research. For example, if you were an engineer tasked with building a bridge, you would need to know the project criteria (e.g., the bridge must span 100 feet and be able to support 20 cars driving over it at once) and constraints (e.g., budget). You would also need to do research on the types of materials you could use to build the bridge. In today’s activity, you are mimicking materials engineers and conducting research on composite materials.”

Ask the students to look at Figure 1 and Figure 2 and list the materials that are used to build the house and the car. Have students think about which of the two items are made of composite materials. Ask students to explain their answers in pairs/small groups before sharing with the class.

Show the 1:47-minute video: What is a Composite?

Lead students through an explanation: Composite materials are materials composed of two different elements. The composite is stronger and more durable than the original materials. Composite materials are used in your daily life. For example, the bathtub or the shower stall that you use is made of composite glass fiber and other materials. In addition, window frames are made of fiberglass. A figure of concrete with cement, sand, and aggregate (crushed stone) labelled. A section is magnified to show the materials mixed together in the composite. Figure 3. Concrete is a composite material made of cement, sand, and aggregate (crushed stone).Copyright V. Ryan, 2010, https://technologystudent.com/joints/concret1.html

Show Figure 3.

Ask students: Is this cement a composite? Allow students to share their thoughts and reasoning.

Tell students: Cement used for buildings and bridges is made of different materials such as sand, crushed stone, and cement. Because the material is combined without the use of chemicals, cement can be identified as a composite material.

A figure of an airplane color-coded to show the materials used in its body. A pie chart next to the plane shows the total materials used by weight. Composite materials form 50% of the plane’s structure. Figure 4. Usage of various materials in the Boeing 787 Dreamliner.Copyright B.S.Kukreja, 2009, https://www.appropedia.org/Composites_in_the_Aircraft_Industry#/media/File:Composites01.jpg

Show students Figure 4. Have them turn to a partner next to them and discuss: Is this plane a composite? Why or why not?

Tell students: Vehicles such as planes and cars are made of composite materials that are lightweight and less expensive.)

In this experiment, we are going to act as materials engineers and look at how composites change the strength of paper. This is research, an important part of the engineering design process. Similar to how engineers researched different materials to build objects such as cars and planes, we will research composites and paper. How much mass does it take to tear one paper strip versus a combination of paper strips? Does combining paper strips impact the strength of the paper? Let’s research the problem and find out!

Background

Composite Materials

A composite material is composed of two materials with different physical and chemical properties. The materials are merged together into one structure, yet they do not completely blend together. Concrete, for example, is a composite material formed from a mix of cement, aggregates (gravel, crushed stones), and sand combined with water.

The composite material is stronger and more durable than the original materials. Using composites can also create a result that is cheaper and lighter than using non-composite materials. The use of composite materials is common; they can be found anywhere from concrete structures to backyard decks, cars, and airplanes.

Engineering Design

Engineers follow the engineering design process to develop solutions to design problems. The design process includes 1) Identifying the Needs and Constraints, 2) Researching the Problem, 3) Developing Possible Solutions, 4) Selecting a Promising Solution, 5) Building a Prototype, 6) Testing and Evaluating the Prototype, and 7) Redesigning as Needed. This activity engages students in the Research step of the design process. Students mimic materials engineers to learn about composite materials and test the strength of composite paper.

Instructions: Materials Matter Activity 2

Steps:

Take two to three sheets of paper and cut them into 4 cm by 8 cm strips.
After cutting the paper into strips, take out one strip, then two separate strips, then three separate strips, then four separate strips, and then five separate strips.
Take two strips of paper and glue them together using a glue stick or glue.Paper strips being glued together.Copyright Parvathy Pillai, 2023
Repeat Step 3 and glue three strips of paper together.
Repeat Step 3 and glue four strips of paper together.
Repeat Step 3 and glue five strips of paper together.
Reinforce the top part of each of the combined paper strips with clear or packaging tape.Top part of the strip being reinforced with tape.Copyright Parvathy Pillai, 2023
Punch one hole on the top and bottom parts of the combined strips (1 to 1.5 cm away from the top and bottom.
Cut five pieces of yarn/string that are 30 cm long.
Tie one end of the yarn/string to the top hole of the paper strip.
Tie the other end of the yarn/string to the ring on the ring stand. The reinforced part of the paper is tied to a string and attached to the ring on the ring stand.Copyright Parvathy Pillai, 2023
Repeat Steps 10 and 11 for the other four paper strips. Make sure the strips are hanging at an equal distance.
Attach a hanging 100 g mass to the bottom hole. Wait for two minutes.
Attach a second 100 g mass to the first one. Wait for two minutes.
Keep adding 100 g until the paper breaks. You could change from 100 g to 500 g masses as the paper strips increase.Paper strip with hanging masses.Copyright Parvathy Pillai, 2023

Before the Activity

Gather materials and make copies of the Materials Matter Activity 1 Worksheet (PDF) and Materials Matter Activity 2 Worksheet (PDF) one per group.
Provide links to videos on the Materials Matter Activity 1 Worksheet by posting in Google Classroom or another accessible location; alternatively, give students digital versions of the worksheet, which includes hyperlinks: EXPERIMENT: HAMMER VS FRUITS (3:58 minutes) and Machine Breaking Different Material (30 seconds)

With the Students

Day 1

Allow students to work in small groups of 3-4.
Distribute copies of the Materials Matter Activity 1 Worksheet (PDF).
As students watch the videos and complete the worksheet, walk around and check on groups. Ask them to explain their answers and ensure that each student has completed their own worksheet.
Lead students through the Introduction/Motivation section.
Ask students to reflect on the videos and review their worksheets. Given what they learned about composite materials, have them discuss which, if any, materials from the videos are composites. Allow groups to share their predictions and reasoning with the class. Note: Out of the materials in the videos, plywood is the only composite. Note that it took the most force to break (328.5 lbs.), and composites are often very strong.

Day 2

Have students return to their small groups. Assign roles such as task manager, material controller, data collector, and safety manager.

- Task manager: Ensures that the group follows the steps of the procedure in order.
- Material controller: Gathers materials and follows directions to assemble and work with materials as needed.
- Data controller: Gathers and records data.
- Safety manager: Ensures that the group is following correct lab safety procedures.

Remind everyone to follow lab safety procedures.
Distribute copies of the Materials Matter Activity 2 Worksheet (PDF). Have the task manager instruct the material controller on which materials to gather and instruct the safety manager to review lab safety with the group before starting the activity and letting the data controller gather data.
Allow students to work through the worksheet. Walk around the room to monitor progress and answer any questions. As needed, show students how to glue the strips together and where to punch the holes.
After students finish gathering data, check that they are working together to answer the Questions and Conclusion on the worksheet.
As a class, discuss the Conclusion. Students should share how they found that composite paper was stronger than one strip of paper, and that adding more strips of paper to the composite resulted in a stronger material.
Remind students that they just researched and tested composite paper, similar to how materials engineers research and test composite materials made of wood, metal, and/or plastic. Ask students: “If you were tasked to build a paper bridge to support 2 kg of mass, would you use a single piece of paper or a composite? If a composite, how many strips of paper would you use? Why?” Allow students to discuss with their groups and use the data they gathered to support their answer in a class discussion.

Have students use the engineering design process to build a bridge using different materials and test their strengths.

Tell students the design criteria and constraints:
- The bridge must span 15 cm (approx. 6 in.).
- Students can only combine a max of two types of materials to create a composite.
- Each group must use different materials or combinations of materials.
Show students various materials (e.g., paper, cardboard, cloth, etc.).
Allow students to brainstorm which materials to use and how to build their bridge.
- Require students to come up with at least three brainstormed designs.
- Encourage them to use the research they recorded on the Materials Matter Activity 1 and 2 Worksheets to aid their brainstorming.
- Let students research different types of bridge designs. Remind students that engineers do not have to invent brand new designs; they can build on existing ideas and modify them to best solve the given problem.
Have students select one design to prototype and test.
- Encourage students to list the pros and cons of each design and use the information they researched to justify their decision.
- Once students have selected one design, have them write their chosen materials in a data table on the board.
Have students gather materials, build, and test their designs.
- Monitor their progress, and once students are ready to test their designs, provide various weights.
Have students record how much weight their bridge can support.
- Encourage students to keep adding weight until the bridge breaks.
- Once they determine the maximum weight their bridge can support, have them write that weight on the board.
Have students reflect on their bridge.
- Ask students: “What worked? What didn’t work? Which material(s) supported the most weight? How would they improve their designs?”
Let students use what they learned from their first design and the class data to iterate on their designs.
After students have had a chance to iterate once or twice, discuss the results as a class.
- Ask students, “Which material or combination of materials were used in the strongest bridge? Why did that bridge support the most weight?” Student answers will vary, but they should support their answers using evidence gathered from their tests.
- Ask students, “Based on the design process you just did, could you recommend the best material to use to build a bridge that would always support the most weight?” Encourage students to notice that they did not test every possible material/composite material they could use to build a bridge, so while they can recommend the best material based on those tested, there is more research and testing needed before recommending the best overall material.

Younger students and lower-grade students can just complete the table and the graph. They can also make observations about other objects that are composite materials. For younger students, teachers can perform a lab demo and start a class discussion of why the combined paper strips hold more mass than the one strip of paper.

More advanced students can create a composite material that can hold the same amount of mass as the combined strips of paper.

Summary

Engineering Connection

Learning Objectives

Educational Standards

Common Core State Standards - Math

Next Generation Science Standards - Science

Materials List

Worksheets and Attachments

Pre-Requisite Knowledge

Introduction / Motivation

Procedure

Vocabulary

Assessment

Safety

Extensions / Scaling

References

Copyright & Attributions

More Like This