Chemistry & Creation of Making Plastic Parts

ACP Lesson Plan 

Chemistry of Making Plastic Parts
Trevor Derksen
Subject(s)Chemistry, Technology Education
Grade Level(s):
11th & 12th
Total Time:
4 to 6 -55 min. Classes

Overview / Description:

In this unit, students will be able to explain and demonstrate how plastic parts are made and understand the chemistry involved in making different parts to meet different customer requirements. As a summative assessment, students will be creating and testing their own DIY injection molding machine.

Learning Goals/Objectives:

After completing this activity, students should be able to:

  • throughly explain the concept, process and chemistry of plastic injection molding
  • demonstrate the process using a "Makerbot" or other similar machine

Workplace Readiness Skill: 

X     Social Skills  X Communication 
 X  Teamwork     X    Critical Thinking
 X  Attitude and Initiative  X  Planning and Organization
 X  Professionalism    Media Etiquette

Content Standards

Common Career Technical Standards

Career Development

CD4: Students will identify and apply employability skills. \

CD4.a.6.h: Evaluate how self discipline, self-worth, positive attitude and integrity displayed in a work situation affect employment status. 

Wisconsin Standards for Technology and Engineering


MNF1.d: Select, use and identify manufacturing processes such as casting, forming, machining, joining, rapid manufacturing (CNC) and treating/coating.

MNF1.d.6.h: Demonstrate the interchangeability of parts increases the effectiveness of manufacturing processes.

Wisconsin Standards for Science

Physical Science - Three-Dimensional Performance Expectation

HS-PS1-5. Apply scientific principles and evidence to provide an explanation about the effects of changing the temperature or 26 concentration of the reacting particles on the rate at which a reaction occurs. 

HS-PS1-6. Refine the design of a chemical system by specifying a change in conditions that would produce increased amounts of products at equilibrium.

Scale, Proportion, and Quantity

Standard SCI.CC3: Students use science and engineering practices, disciplinary core ideas, and an understanding of scale, proportion and quantity to make sense of phenomena and solve problems.   

Disciplinary Core Ideas:

SCI.PS1.B.h Chemical processes are understood in terms of collisions of molecules, rearrangement of atoms, and changes in energy as determined by properties of elements involved.

SCI.ETS1.C.h Criteria may need to be broken down into simpler ones that can be approached systematically, and decisions about the priority of certain criteria over others (trade-offs) may be needed. 


Download: Molding_Student_Handout.docx

Learning Activities:

WHO (T=Teacher Focus Lesson; WG=Whole Group\; SM=Small Group; I=Independent)

Learning Activity Task                                                WHO is responsible
for this step?
Approximate time
for task
Day #1

Teacher will conduct teacher directed lesson plan:

     a. Hook - Have you ever been on vacation and created a souvenir from a machine such as this: If you have, then you have seen injection molding in action.

     b..Describe what plastic injection molding is and briefly explain how parts are made. The following video (3:38) may be used as an introduction to plastic injection molding with Legos:

    c. In small groups, have students brainstorm a list of items which they believe are made from injection molding. The teacher might create categories and have each group brainstorm items just within their category (i.e. food and beverage, medical, construction, etc.). Share out with the class.

    d. Demonstrate/show various everyday items made by injection molding (see list of items in Materials for suggestions).

   e. It is recommended that the students spend some time learning about the chemistry behind injection molding. See the linked articles above to have students work independently or in pairs to learn the science behind the production of plastics.

Alternatively, explain that another method of creating plastic items from resin is 3D printing. There are various types of 3D printing, but the following videos showcase some of the most cutting-edge 3D printing:

Teacher55-110 min.
Day #2

Teacher will start shifting from teacher-directed to teacher-guided session by helping students to start and finish their machine project research time and assignment. 

            a. Explain that students will be researching injection molding and then creating their own process to mold an object.

           b. Have students complete the Chemistry of Plastic Mold Injections Research Notes linked in the Student Handout above.

            c. Have students watch the video below on how to make a DIY injection molding machine - DIY Injection Molding Video: (This video is a great step-by-step video on how to make your own injection molded part.)

3.  Students will plan and create their "DIY Injection Molding" machine. Students will follow the DIY Plastic Mold Injection Instructions found in the Molding Student Handout above.

Teacher/Student55-110 min.
Day #3 & #4

     a. These will be a student-driven classes with teacher supervision.

     b. With the teacher's assistance, after safety instructions, students will build and test their creations.

     c. After teacher approval and additional safety instructions, students will make their designs using hot glue or material of teacher's choosing.

     d. Safety Procedures/Rules:

  • Burn possibility from the hot glue gun and glue
  • Inhalation hazard from the releasing agent
  • Cut hazards exist when using scissors or knives
  • Safety goggles must be worn.
Student/Teacher55-110 min.

Assessment: Observational & Project/Presentation

Formative Assessments - 

1. Along the way, the teacher will use observational checks as well as homework/lab checks to ensure that students are on track to complete this project on time.

2. Students will be asked periodic questions so that they can show understanding of the material they researched as well as be able to explain what is going on at different points in the building process. Examples of questions include:

Summative Assessment - 

Download: DIY_Injection_Molding_Project_Rubric.pdf


Students will give a brief report on planning and building their injection molding machine and show the class their final product.

Extension Activity (for intervention or enrichment):

IEP/504 Students: Depending on their level of proficiency, students can create a report/Powerpoint/ or work alone to build a machine with extended time.

Higher-Level Student: These student can be tasked with making more complicated injection molding machine to create a more detailed final product.

All Students: Can/will be tasked with completing a choice project of either a simple process machine, a more complicated machine or a paper, a different but similar project, or a powerpoint explaining the processes involved.

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