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Sports Helmets and Impact Testing of Polymers

Grades: 5-8
Author: Sandy Van Natta
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Abstract

Module Description

In sports, participants may be subjected to collisions with balls or other people or even crashes on bikes and skate boards. How is it possible for athletes to tolerate such blows and still "remain in the game"? This module allows participants to use inquiry to investigate the materials used to make sports helmets, a modern form of body armor. The participants will perform impact tests on plastic (polymer) samples by dropping a plumb bob from differing heights onto to the samples. The test, modeled after actual industrial testing methods, will measure the brittleness of a material that has been subjected to an intense blow. Both "hard" plastics that may be used in the outer shell of a helmet and foamed plastics that can be used for the inner lining of the helmet will be tested. The participants will use data gained from their tests to determine which plastics they feel are most suitable for usage in a helmet.

A discussion of the use of science and technology to aid and protect humans will flow from this lesson. As participants examine and determine the properties of various materials they will be mimicking the scientific and technological processes involved in designing a consumer product for market.


Objectives

  • Participants will identify the functions of the hard outer shell and the foamed inner lining of a sports helmet.
  • Participants will distinguish between the structure of a helmet made for multiple collisions, such as a football helmet, and a helmet made for a single collision, such as a bike helmet.
  • Participants will work cooperatively.
  • Participants will perform tests on materials designed to mimic actual industrial tests and collect data.
  • Participants will examine and analyze data collected from the testing of polymers to determine which plastics would be most suitable for use in a helmet.
  • Participants will design and make a miniature helmet based upon their data analysis.
  • Participants will discuss how they can use this, or a similar activity, in their own classrooms. They will design a lesson plan that will incorporate such an activity into their existing curriculum.

Materials

The total cost for running a session for 20 to 30 teachers will be about $200 if materials are purchased from Education Innovations (this is for 5 complete set-ups). If you gather materials yourself, the cost will be about $75. However it may take time to find sources for the plastic samples needed.

Materials needed per group:

  • Samples of a variety of hard plastics cut to nearly the same size (polyethylene, polycarbonate, ABS, plex-iglass, polypropylene, etc)
  • Samples of a variety of foamed plastics (hard and soft polyurethane foams, expanded bead and "regular" polystyrene, foam rubber, cross-linked polyethylene foam, etc)
  • Clear tube at least 30 inches long
  • Plumb bob or other standard weight
  • String - at least 36 inches
  • Piece of wood about 4 inches square and at least 1 inch thick
  • Safety goggles - 1 pair per each group member
  • Ruler or meter stick
  • PVC coupling 1 and ½ inch diameter or a small jar lid
  • Several miniature flat chocolate candy bars
  • Small plastic Easter or sports eggs - optional - needed only if participants design their own helmet
  • Small hollow or cream filled chocolate balls - small enough to fit inside the plastic egg - only needed if helmets are designed
  • Gloves - optional
  • Video showing a football tackle or a fall from a skateboard or bike for the engagement phase

Procedures

The entire student lesson plan Sports Helmets and Impact Testing of Polymers can be found on the AGPA website. Complete directions for conducting this activity are included.

A brief overview will be given here with emphasis on running a professional development session.

Engagement

In this phase you want to get participants to think about the tremendous blows an athlete may be subjected to during participation his/her chosen sport. A short video clip showing a football tackle or a fall from a bike or skateboard can be used to catch their attention. Once the group has determined that protective body equipment is needed to minimize injury, ask the participants what types of materials are used to make most protective sports equipment. Lead the group to the conclusion that most protective equipment is made of plastic. The group should think about how important the role of plastics is in sports safety. Group members may want to share some of their own "stories" involving sports accidents and the role of safety equipment.

Assessment: In this section the PPD can see if teachers are actively involved in group discussions. This evaluation can be verbal and informal.

Exploration

Participants will perform several tests on various types of "hard" and foamed plastics. Some of the plastics tested will be the actual plastics used in sports helmets today.

Assign the participants to work in groups of 4. (However anything from groups of 2 to 6 will work.) The participants can perform the tests as written in the module. If time is limited, you may only wish to have teachers perform the impact tests from heights of 6 and 30 inches. The data chart provided in the module can be used for recording data. If teachers do not wish to write on their own copy of the module, you may wish to run off separate copies of the data sheets. Allow time for each group to record their data and discuss their results.

Assessment: During the exploration section, walk around to each group to see if they are completing all data charts and following reasonable laboratory procedures. Think of your participants as engineers. Are they performing as expected?

Explanation

In this stage, the groups report their findings and look for patterns in their test results. Questions can be answered and new terms can be introduced.

Whatever results each group receives in their testing are acceptable. Normally, plexiglass is the first hard plastic to break, but all plastics may show slight indentations. Ask what the participants would consider as product failure in a plastic designed for a helmet's outer shell. Since the outer shell must be impact resistant and keep the foam next to the head, would a small indentation detract from the functionality of the helmet? (Not all groups may agree on the answer to the questions. As long as they can support their opinion with data, any answer should be acceptable.)

Ask which outer shell polymers seemed the best at absorbing shock. Most groups will find that the ABS or ultra-high molecular weight polyethylene had the least indentation during testing.

When examining foams, the type of helmet needs to be specified. Football helmets have a soft inner lining designed for multiple collisions. Bike helmets have a rigid foam designed for use in one collision only. Ask participants which foam they would prefer for use in the football helmet and which for a bike helmet. Participants may choose either the rigid polyurethane foam or the beaded polystyrene for a bike helmet but the crosslinked polyethylene for the football helmet. (Answers will vary based on the types of foams available for testing.)

Assessment: Use the quality of discussion to evaluate the Explanation section. When teachers discuss the outcome of each test, have them relate the testing results to the physical properties of the plastic.

Elaboration

Have teachers discuss how they would apply what they have just learned in their classrooms. They can formalize their plan implementation by designing a lesson plan using the lesson plan template provided at the end of this activity.

Assessment: Make sure the discussion emphasizes ties to science and technology. Teaching physical properties is common in physical science courses, however teaching how those properties can be utilized ties the "science" into the importance of producing products for daily lives.

A New Exploration

Have the participants design a miniature helmet using the knowledge they have gained during their testing. Each participant can be given ½ of a plastic egg shell or ½ of a plastic sports ball shell (sports ball shells are available and in the same general store location as the eggs at holiday time) to be used as the outer shell of a helmet. Ask each participant to design and make a lining for their "helmet". The helmet must protect a round hollow or cream filled chocolate ball during an impact test drop of 30 inches.

Each participant can be given their helmet shell to take home and line with whatever shock absorbing material they choose. Helmets can be brought back to the group for testing at a future date if possible. You may want to give small prizes for any helmet which protects the chocolate ball during the impact test.

Assessment: The "survival" of the chocolate ball can be used as the assessment for this activity.


Rationale

The current science standards require that participants do more than just read about technological advances. The participant must become actively involved in tying science and technology together. This module is an exemplar of a science and technology unit. The module allows participants to be actively engaged as they investigate the tie between science and sports as they examine materials that could potentially be used in protective sports equipment. This module uses the learning cycle to take participants through the major steps of a scientific investigation. When posed with a problem of choosing materials to be used in a sports helmet, participants must be aware of the differences between helmets used in various sports and the physics behind these differences. Participants must test materials using procedures that mimic actual industrial tests. They must make decisions among their groups as to what results will mark a plastic for potential use in a helmet and what will determine product failure. After collecting data and studying the differences in helmet types, the participants can be encouraged to design and "manufacture" their own miniature sports helmet. This process can involve research in addition to utilization of the data collected. The participant is exposed to the same processes an industrial company must go through in order to design, and develop a new product. This is as close to "real world" science as the participant is likely to get. If teachers go back to their classrooms and try this module with their own students, they will find that their students will be actively involved and have a great deal of fun while learning science concepts, procedures, and processes.


Science Standards

Content, Technology, and Professional Development:

NSES Content Standard A: Science as Inquiry: as a result of activities, in grades 5-8, all students should develop:

  • Abilities necessary to do scientific inquiry.

NSES Content Standard B: Physical Science: as a result of activities, in grades 5-8, all students should develop an understanding of:

  • Properties and changes of properties in matter.
  • Transfer of energy.

NSES Content Standard E: Science and Technology: As a result of activities in grades 5-8, all students should develop:

  • Abilities of technological design.
  • Understanding about science and technology.

NSES Content Standard G: History and Nature of Science: as a result of activities in grades 5-8, all students should develop an understanding of:

  • Science as a human endeavor.

NSES Professional Development Standard A: Professional development for teachers of science requires learning essential science content through the perspectives and methods of inquiry.

NSES Professional Development Standard B: Professional development for teachers of science requires integrating knowledge of science, learning, pedagogy, and students; it also requires applying that knowledge to science teaching.

National Education Technology Standards:

3. Technology productivity tools:

  • Students use technology tools to enhance learning, increase productivity, and promote creativity.

5. Technology research tools:

  • Students use technology to locate, evaluate, and collect information from a variety of sources.
  • Students use technology tools to process data and report results.

Best Teaching Practices

  • Authentic Problem Solving
  • Inquiry
  • Hands-on/Minds-on

Time Frame

Preparation time: If kits are purchased from Educational Innovations, very little preparation time is need. You simply need to buy a bag of small, flat, chocolate candy bars and divide the plastic samples into group sets. If you are gathering materials on your own, you will need time to shop and purchase tubes, plumb bobs, various the plastics, etc. Allow time to gather materials and have some materials shipped to you. It will take several hours to cut all plastic samples to size, label them and assemble the samples into group sets.

Module Lesson Time: 1 to 2 hours. Teachers may be asked to design their own helmets after your session and bring them back for examination at a future time.


Preparation

Each group will need to have a plumb bob, clear plastic tube, piece of wood, a PVC coupling, string, ruler and several candy bars. The plastic samples need to be divided so that each group has one labeled 2" x 2" sample of each type of hard plastic and one labeled 2" x 2" sample of each type of foam. Groups can be anywhere from 2 to 6 people depending on the amount of supplies you have available. If you choose to have participants design their own helmet, have half of a plastic egg shell available for each person.


Safety

Participants should wear safety goggles during experimentation. If a plumb bob would be dropped on a foot from table height, it could cause a lot of damage. Warn participants to hold the clear tube securely with both hands when the bob is dropped. Tell them to keep their hands several inched above the base of the tube, in case one of the plastic samples breaks. You may give the participants the option of wearing gloves if they are worried about plastic breakage (The plexiglass sample will break when impacted by the plumb bob - but do not tell them which samples will break in advance!)


Assessments

Assessments are given after each part of the learning cycle within the procedures.


Explanation of Science

Detailed explanations of the science involved in this module can be found in the student lesson plan.


Handouts

N/A


Extensions

The calculation of impact is a math extension.

A historical look at athletic equipment ties in social studies. Cultural diversity in types of equipment or lack of equipment by athletes from different parts of the world would be an interesting topic of discussion.

One can easily invite and athletic coach to speak to the participants about sports equipment for a given sport at some time before, during, or after the professional development session. This will give a more direct tie to athletics. Extra time must be allotted if a speaker is invited.


Lesson Implementation Template

Download Lesson Implementation Template: Word Document or PDF File


Equity

Be aware of the needs of diverse participants and keep diversity in mind when choosing the groups. Some participants may have little background in sports that use helmets. Group these participants with participants that do have experience in sports with helmets.


Resources

None available for this module.


References

"Impact Testing of Polymers" by Sandy Van Natta, Polymer Ambassador

American Chemistry Council, Plastics in Sports, http://www.americanchemistry.com/plastics

BHSI, Bicycle helmet Safety Institute, Foams used in Bicycle Helmets, http://www.bhsi.org/foam.htm

Interactive Media, Gear Up for Safety, http://interactivemediakit.com/gearupforsafety

NOCSAE, Standard Drop Test Method and Equipment Used in Evaluating the Performance Characteristics of Protective Head Gear, NOCSAE Doc.001-00, Jan. 2002

NOCSAE, Standard Performance Specification for Newly Manufactured Football Helmets, NOCSAE Doc.002-96, May 1998

Riddell, The New Revolution Helmet, http://riddell.com/revfacts.htm

SciTecks: Polymer Research and Development, An Interdisciplinary Modular Curriculum for High School, Pilot Version, American Chemical Society, 1998.