Summary

In this activity students will use unit conversion to help compare sizes of molecules, viruses, and droplets and then use them to interpret graphical data. They will then use their findings to design a cloth mask that helps protect its wearer against infection by SARS-CoV-2, the coronavirus that causes COVID-19.

Grade Level

High School

NGSS Alignment

This activity will help prepare your students to meet the performance expectations in the following standards:

• HS-ETS1-1: Analyze a major global challenge to specify qualitative and quantitative criteria and constraints for solutions that account for societal needs and wants.
• HS-ETS1-3: Evaluate a solution to a complex real-world problem based on prioritized criteria and trade-offs that account for a range of constraints, including cost, safety, reliability, and aesthetics as well as possible social, cultural, and environmental impacts.
• Scientific and Engineering Practices:
  • Using Mathematics and Computational Thinking
  • Developing and Using Models
  • Analyzing and Interpreting Data

Objectives

By the end of this activity, students should be able to

• Compare sizes of molecules, viruses, and droplets, even if sizes are initially given in different metric units.
• Demonstrate how to use graphical data to solve a problem and understand the relevance of chemistry to practical problems.

Chemistry Topics

This activity supports students’ understanding of:

• Molecular Size
• Molecular Structure
• Intermolecular Forces
• Measurement
• Data Analysis
• SI Units

Time

Teacher Preparation: 50 minutes
Lesson: 90 minutes

Materials

• Student Handout
• Examples (digital or real) of masks
  • N95 Respirators
  • Surgical Masks
  • Cloth Masks

Surgical mask (left), N95 mask (right). Images are in the public domain FDA website

Safety

• No specific safety precautions need to be observed for this activity.

Teacher Notes

• Introduce this activity by discussing with students the recommendations of the CDC and the local health department on how to slow the spread of COVID-19.
  • CDC Information About Masks
  • At the time of this writing, the CDC recommended cloth face coverings be used with physical distancing, and hand washing.
• If available, let students examine both intact and cut examples of N95 respirators, surgical masks, and cloth masks. The cut examples would show students the layers in the respirators and masks.
• Provide students with the Video Anticipation Guide handout. Students should analysis the questions and select a response to each statement prior to watching the video.
• Next students should watch the ACS Reactions Video, How Much Do Cloth Masks Protect You From Getting Corona Virus?
• Following the video, the students should again respond to the statements on the anticipation guide. An answer key has been provided for the teacher, and a class discussion is encouraged.
• After the video portion has concluded, students should begin the main activity. This portion of the activity can be completed independently by students at their own pace.
• It might be helpful for the teacher to direct student attention to the bullets points on page 2 of the student handout. These bullets aim to help interpret the data in Figure 2 and 3, and students might benefit from additional teacher instruction related to this information.
• Providing Figure 2 and 3 in color for students to analyze would be beneficial.
• The mask design portion of the activity has been labeled as an optional portion. If students participate in this, they might find it to be interesting to share their mask designs with each other. It is important to help students understand that masks need to be used with other measures such as physical distancing and hand washing.
• Notice to Readers: Permission to reuse figures from ACS Nano 2020, 14, 5, 6339-6347 in this activity was granted by ACS Publications. Further permissions related to the material excerpted should be directed to the ACS.
• References:
  • Mark Fischetti, Veronica Falconieri Hays, Jen Christiansen, Britt Glaunsinger, Inside the Coronavirus: What Scientists Know About the Inner Workings of the Pathogen That Has Infected the World, Scientific American July 2020, Volume, 323, Number 1. Pages 32-37
  • Lili Pike,Why 15 US states suddenly made masks mandatory, America’s 180 on masks, explained. May 29, 2020 https://www.vox.com/2020/5/29/21273625/coronavirus-masks-required-virginia-china-hong-kong
  • Abhiteja Konda, Abhinav Prakash, Gregory A. Moss, Michael Schmoldt, Gregory D. Grant, Supratik Guha, Aerosol Filtration Efficiency of Common Fabrics Used in Respiratory Cloth Masks, April 24, 2020, ACS Nano 2020, 14, 5, 6339-6347, https://pubs.acs.org/doi/full/10.1021/acsnano.0c03252
  • Kimberly A. Prather, Chia C. Wang, Robert T. Schooley, Reducing Transmission of SARS-CoV-2, June 26, 2020, Science, Volume 368,Issue 6498, Pages 1422-1424, https://science.sciencemag.org/content/368/6498/1422