BioEd Online

Teacher Background

The Science

Viruses and other microbes are so small they are measured in micrometers (or microns).  Even smaller particles are measured in nanometers. One micron is 1000 times smaller than a millimeter. An individual SARS-CoV-2 virion is about 100 nanometers across. One nanometer is 1000 times smaller than a micron!

Objectives and Standards

Learning Objectives

Students construct a virus model and compare it to ordinary things using the same scale.

 

Science/Health/Math Skills

Comparing/contrasting

Measuring

Interpreting information

 

NGSS Science & Engineering Practices

Asking questions and defining problems

Developing and using models

Planning and carrying our investigations

Using Mathematics and Computational thinking

 

Materials and Setup

Materials

Each student will need:

Patterns 1 and 2 printed on white cardstock paper or plain white paper; make a few extra copies in case students need to start over

Rectangle of aluminum foil, approximately 4 x 14 cm.

Clear plastic tape

Straight edge ruler

Ballpoint pen

Scissors

Colored pencils or Crayons (A pre-colored version is available for color printers.)

Student Handouts or Electronic Copies

Student Sheet A: Visualizing the Size of the SARS-CoV-2 Virion question sheet (paper or electronic copy)

Student Sheet B: Viruses are Tiny! (paper or electronic copy of student reading material)

Student Sheet C: 3-2-1 Questions (paper or electronic copy)
 

Time:

One or two 45-minute class periods; you may have students construct the virion model in class or as an assignment.

 

Set Up and Teaching Tips

This activity enables students to work individually to construct a virus model. The model is easier to construct and sturdier if made from cardstock. However, it can be made and assembled using plain white paper. In either case, the templates from patterns 1 and 2 must be printed onto the paper or cardstock ahead of time. Students will need to cut the patterns carefully, so have extra copies on hand in case they have to start over.

 

Procedure and Extensions

Engage

1. Ask students, Have you ever seen a virus? [It is not possible to see viruses directly, because they are very small.] Encourage student to share what they know, or want to know, about viruses. List their ideas. Make certain to include the following information as part of the discussion.

   • Viruses are small infectious agents that require living cells to make copies of themselves.

   • Viruses replicate (make copies of themselves) by invading living cells.

   • Most viruses are too small to see with a usual light microscope (such as the kind students have in their biology classes).

   • Viruses are responsible for many different diseases in humans, including the common cold, flu, smallpox, HIV/AIDS and COVID-19 or coronavirus disease. Viruses also infect other animals and even plants.

   • All viruses consist of genetic material surrounded by a protective coat. Some viruses, such as coronavirus, also are surrounded by a viral envelope.

Explore

2. Discuss the purpose of the activity with students. They will learn more about a virus, called SARS-CoV-2 by constructing a paper model that enables them to visualize a single SARS-CoV-2 virus particle. SARS-CoV-2 stands for Severe Acute Respiratory Syndrome CoronaVirus 2.

3. Demonstrate how to cut and fold the model from the cardstock or paper templates.

4. Also demonstrate how to measure and fold the rectangle of aluminum file to create a long narrow strip about 1 cm by 14 cm. Once folded, twist the strip three or four times to create a helix. When students create the strips, have them set the strips aside until they have almost completed construction of the paper sphere. This strip represents the capsid with genetic material.

5. Tell students that detailed instructions are included on the two patterns for making the model. Reiterate important steps in constructing the model.

• Make sure students use care in cutting of the patterns to yield the best models.

• Make sure students score the dashed lines with the ruler and ballpoint pen. This is particularly important if they are constructing the models from cardstock.

• Have students tape together the matching edges of each of the five model parts before joining them together. Students may want to cut several small pieces of tape in advance to facilitate folding and taping the edges of the sections.

• Taping from the inside makes the neatest looking model. However, the last few hexagons and pentagons will have to be taped on the outside.

• Students should insert the aluminum strip representing the capsid inside the model before taping it closed.

 

Explain

6. Have each student measure or estimate the diameter of their virus models. Ask, since the model is not a perfect sphere, what is best way to measure it? Discuss different ways to estimate the diameter of the model.

7. As students will observe, when constructed, the virion model is approximately 10 cm across. This is one tenth of a meter or 100 million nanometers. The actual virion itself is about 100 nanometers across. That makes the paper model one million times larger than the virus. One million anything is hard to imagine!

8. Discuss the size of the virus particle.

   • An idea of the size differences can be gained by looking at a common object or person of a known size, then multiplying that size by 1 million. A person 1.524 meters tall (5 feet) would become 152,400 meters or 1,524 kilometers tall (947 miles). Ok, that is not easy to imagine either!

   • Try this on for size. A grain of sand 1 mm in diameter multiplied by 1 million would become a boulder 1 kilometer in size compared to the paper model. That’s asteroid size.

9. The last word about the model is its shape. The virion is actually spherical. This model is a paper version of a small soccer ball. It has 20 hexagons and 12 pentagons and rolls easily. Making a perfectly spherical paper model with this technique would be very difficult.
    

Extend

10. Optional Project: Challenge students to create a virus calculator using a data-organizing spreadsheet program. Using 100 nm for the size of the SARS-CoV-2 virion as the denominator, the calculator should quickly determine the size comparison of common object selected by the students.

Evaluate

11. Have students read the accompanying essay, Coronaviruses are Tiny! After reading the essay, students should create a 3 -2 -1 chart about SARS-CoV-2 using the template provided or in their science notebook.

    • 3 Things You Found Out or Learned About Coronaviruses

    • 2 Things Surprising Things that You’d Like to Learn More About

    • 1 Question that You Still Have

Handouts and Downloads