Author: William E. Dunn
Source: An authentic assessment born of the need to solve a common problem. Removal of chewing gum from hair, clothing, or surfaces.
Our lives are fraught daily with things that gum up the works; especially chewing gum. If it happens to attach itself to your clothes, hair, or (heaven forbid) the inside of the family clothes dryer you have a real problem.
What should students know as a result of this lesson?
What should the students be able to do as a result of this lesson?
Chewing gum polybutadine?, bubble gum, solvents, vinegar, mineral oil, clothes iron, metal spoons.
We have all chewed gum. Awaken with it entangled in our hair – on our face, clothes, and nose --in our pockets and in the dryer. As a nuisance, it ranks right up there with permanent marker graffiti, and fruit stained furniture.
Students should understand that polymers are long chained molecules made of many repeating units called monomers.
Students should understand that cross linking is a form of side chained bonding found in polymers chains.
Students should have basic lab skills. The chemicals and temperatures in this lab are generally safe, but students need to be able to work safely in lab.
How do you remove chewing gum or bubble gum (Polyethylene); (Polyvinyl Acetate); (Polyisobutylene) from???
Before beginning any handling of materials, remind students to work safely and to use materials/equipment for the intended purposes.
Ask, "Which of the physical properties should we test?" Accept input. Lead them to identify the following in the procedures below: Also, conduct a discussion on how they will record their observations and tests. (Each student can test his/her own or groups can test several polymers (gums).)
For each polymer (gum) perform the following: Determine the density of your sample by placing the sample in water, (the first test solution) provided by your teacher. Record whether the sample sinks or floats in water and decide the approximate density. To find a more precise density for each sample, mass your sample, find the volume by water displacement, then divide mass by volume to calculate density. Compare your results with the tests performed by other groups.
Describe the polymer to include color, hardness, flexibility, opaque or transparent, odor, etc. and record your observations on the data sheet. Compare your results.
Assessment: Distinguish types of bonds: physical versus chemical bonds. Which of the method(s) worked best to break the bonds?
Students will work in small groups of 3-4 to explore which substance or methods (I-V) works best to remove chewing gum or bubble gum from cloth samples. Describe and draw the bonds on the molecular and atomic level.
Which procedure will work best to break the physical bonds?
Which procedure worked best to break the chemical bonds?
Students will be able to explain the processes of chemical bonding, physical bonding, and thermal reactions, on a macro and sub-microscopic (molecular) level.
Assessment: students can explain and demonstrate a mastery of vocabulary: chemical bonds; cross-linked; molecules; monomers; polymers; physical bonds; shirring forces; solvent; thermal energy. Also, how cross-linked bonds can be shirred or broken – by mechanical, thermal, or chemical means.
Students will be able to demonstrate by balancing equations and demonstrating how energy bonds are formed and broken.
An authentic assessment (lab) will show: how bonds are formed and broken; thus proving the laws of conservation of mass and conservation of energy.
Students will need to understand : atomic structure; sub-atomic location, and charge. As well as, electron configurations.
Common Core Standards:
Polymers are long chained molecules made of many repeating units called monomers
Cross linking is connecting polymer chains through side chained bonding.
Neither student-centered learning nor hands-on learning is as effective when children confront concepts that are not applicable to their own lives. This supports the idea that knowing a concept is being able to apply it; indeed, scientific information and its applications do become more meaningful when children can tie them to their real life experiences. Children engaged in authentic problem-based learning apply their science knowledge to questions they have about why things happen in their world, and they discuss the social ramifications that are often associated with scientific concepts.
Assessments will be formatted to International Baccalaurate (IB), National, and State Common Core standards and Pro core assessments.
Labsheets will be from Investigations in the "Foundations of Physical Science, with Earth and Space Science" by Thomas Hsu.