Some Similarities between the Spread of an Infectious Disease and Population Growth

In the lab, Some Similarities between the Spread of an Infectious Disease and Population Growth, a simple simulation demonstrates exponential spread of infectious disease in a population, and discussion questions develop student understanding of how human diseases spread. Additional discussion questions and a graphing activity develop an understanding of exponential and logistic population growth.

Download Student Handout: PDF format or Word format

Download Teacher Preparation Notes: PDF format or Word format

We invite comments on this Hands-On Activity and the accompanying Teacher Preparation Notes, including suggestions for other teachers who are planning to use the activity, useful preparatory or follow-up activities, additional resources or any questions you have related to the activity, or a brief description of any problem you might have encountered. If you have a relevant Word document you would like to have posted on this comments page, such as a version of the protocol you have used in your classroom, or if you would prefer to send your comments or questions in a private message, please write Ingrid Waldron at

See also a complete list of activities:
Hands-on Activities for Teaching Biology to High School and Middle School Students



Serendip Visitor's picture


I've just been looking at the "Evolution by Natural Selection" worksheets. Can you please correct the grammar when you use "different"? The preposition which goes with "different" is "from" not "than".

I would also appreciate English spellings of words like colour. I realise that Americans spell things differently, but I'm in Australia where we speak and write English, not American.

iwaldron's picture

2012 revision

The Student Handout has been revised to improve clarity and make the activity more concise and more focused on exponential and logistic growth curves. Revisions of the Teacher Preparation Notes have clarified the instructions.

Serendip Visitor's picture

Make NaOH solution

I used household baking soda. I added about a teaspoon of baking soda to about 1/4 cup of tap water.

I used a "homebrew" pH paper to test.

iwaldron's picture

Preparing NaOH solution

The safest way to prepare a clear solution with a basic pH of 10 or above is to use Calgon or Borax. 

To use NaOH pellets we think the best approach would be to prepare a 0.25 molar solution, dissolving the appropriate number of pellets in water and using gloves and goggles for safety. 

Either way, you will want to check to make sure that your solution when diluted to 1/8 strength will still change color when the pH indicator is added.


Ingrid Waldron and Jennifer Doherty


Anonymous's picture

NaOH Solution

What is the best and safest way to prepare this NaOH solution? I have access to NaOH pellets- any idea how I can use these?

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