Talking Math and Coronavirus With Your Kids #tmwyk

Nothing like a global pandemic to spark a good math conversation.

If you’re a parent from Alabama, Florida, Illinois, Kentucky, Louisiana, Maryland, Michigan, New Mexico, North Carolina, Ohio, Oregon, Pennsylvania, Rhode Island, South Dakota, Virginia, Washington, West Virginia, and Wisconsin — and by the time this post is published, probably many other states — then you’ve got several weeks of quality time with your kids ahead of you. You may be wondering what you can do to fill their time in meaningful and productive ways. Well, my recommendation is to talk math any time you’re with your kids, but while COVID-19 is in the news, that suggestion may be more important than ever.

It won’t be long before you tire of questions from your kids about why they have to spend the next two to four weeks at home, about why you won’t let them go to the mall, about why their friends can’t come over, about why they shouldn’t play tag or duck, duck, goose. But don’t get frustrated by their questions. That curiosity is an opportunity to talk about the math of the pandemic while reinforcing the reasons for staying home.

The spread of any disease is dependent on four factors:

• the population of opportunity;
• the number of days an infected person remains contagious;
• the number of people with whom an infected person comes in close contact; and,
• the likelihood of contraction when close contact occurs.

Simulations based on these four factors can be conducted with the NCTM Pandemics app (which, unfortunately, requires Flash). The page on which that app resides talks about swine flu, because the app was developed in 2006. But the lessons to be learned from the app are as relevant today — maybe even moreso — as they were 14 years ago.

You can explore on your own, or you can watch the screencast below to see how the spread of coronavirus can be controlled if we all do our part to limit close contact with others.

With your kids, research and discuss appropriate numbers for each factor.

• For display purposes, the app limits the “population of opportunity” to 400. This number falls significantly short of the nearly 8 billion people worldwide who might be infected with coronavirus, but it’s enough to make a point.
• The number of days an infected person remains contagious is unknown, but healthline says that “people who have the virus are most contagious when they’re showing symptoms” and the infection starts with mild symptoms that “gradually get worse over a few days.” It’s reasonable to estimate that an infected person might be contagious for three to five days.
• The number of contacts is the only factor over which we have control. If you go to work or a shopping center, you may have contact with 20 people a day; if your child goes to school, she may interact with 50 other students. But if you follow CDC guidelines, stay home from work or school, and avoid public gatherings, you can reduce the number of contacts to just a handful.
• Finally, the chance of contraction is unknown. What is known is that an infected person is likely to transmit COVID-19 to between 2.0 and 2.5 other people if some type of quarantine does not occur. The corresponding chance of contraction would be in the range of 2-4%.

To convince your kids that staying home is a good idea, run the simulation with a large number of contacts. Even if the number of days contagious and chance of contraction are low, most of the population will become infected if the number of contacts is high. But then reduce the number of contacts and run the simulation again. As the number of contacts decreases, so, too, will the percent of the population that gets infected as well as the number of days before the pandemic burns itself out.

Of note, most of the population will be infected if the days contagious and chance of contraction are both high, regardless of the number of contacts. For instance, if days contagious and chance of contraction are both set to 10, then more than 80% of the population will be infected in the vast majority of simulations, even if the number of contacts is set to 2. However, there are very few diseases for which a person remains contagious for 10 days and the chance of contraction is 10%; and, those numbers are certainly higher than the data would suggest for COVID-19.