Parts Per Million Activity

Required materials:

eyedropper, water, graduated cylinder (10 mL graduations), clear plastic cups, markers, food coloring


“Parts per million” is a scientific unit of measurement that counts the number of units of one substance per one million units of another. But because it’s hard to conceptualize really large numbers, it can be difficult to wrap our brains around what “one part per million” really means. Kim Preshoff (with help from 100+ animators from the TED-Ed Community) shares nine helpful ways to visualize it. Take this concept further with your choice (or both!) of the two lessons above.


The Rutgers Engineering Planet lesson plan calls for masking tape, but the cup itself can be labeled with a permanent marker. For the Country Club Ichthycide Lab, egg platters can substitute the Chemplates. The more affordable option is to use cups, so it is up to the teacher's discretion whether to use cups or the platters/Chemplates. Also, the eyedropper can be substituted by an empty food coloring bottle.

NGSS alignment:

1. Asking questions (for science) and defining problems (for engineering) 4. Analyzing and interpreting data 5. Using mathematics and computational thinking 6. Constructing explanations (for science) and designing solutions (for engineering) 8. Obtaining, evaluating, and communicating information