Saturday, February 11, 2012

P.E.O.P. -- How many drops of water can sit on a face of a penny?

One of the discrepant events that works well with Smarter Science’s Predict – Explain – Observe – Explain (P.E.O.P) templates is “How many drops of water can sit on the face of a penny?” This activity is simple to set up; all you need is some pennies, medicine droppers and water. The unexpected results will lead to endless fascination, excellent questions, numerous investigations, opportunities to record, plan, design, gather data and experiment as well as  interpretation by comparing, contrasting, analyzing, evaluating, and the communication skills of discussing, explaining, reflecting and reporting.
My grade nine applied science class performed a P.E.O.P. such as this as part of their Culminating Performance Task (CPT) this past semester. The students were given one Canadian penny, a medicine dropper and the P.E.O.P. template at the introduction of the activity. This allowed all the visual learners to see just what size the dropper and the penny were prior making their predictions.
Students were instructed to make their predictions using an “If . . .then . . “ statement in box one of the template and to include a diagram. Predictions ranged from 2 to 8 drops with the mean being 4 drops of water.
In box two of the template they were to explain why they had made their predictions. Most of them wrote something along the lines that “pennies are small so not much water would fit on them”. In my class of 19 students there were neither outstanding or startling predictions nor explanations.
After completing box one and two of the template the students then got beakers of water and began their experiment. This may have been the only moment of time, during the entire semester, that my classroom was silent! The students were intent on this task, it thoroughly captivated them. Quite frankly they couldn’t believe what they were observing! They wanted to repeat it over and over again to ensure that their results were indeed reproducible, just like “real” scientists! Eventually, yet begrudgingly, I had them stop their experimentation so they could complete their written work and thereby provide me with documentation towards their final mark. 
In box three of the template the students recorded how many drops of water they were able to fit on the face of a penny, incredibly the highest number was 54! Although each and every student had disproved their initial prediction they were proud of their accomplishment and insightful in explaining their reasoning into why their predictions were wrong.
This simple P.E.O.P. allowed my students to not only engage in a rich, authentic task but it also allowed them to demonstrate their critical thinking skills while demonstrating how they have evolved into real scientists over the semester, not only in the all of their actions that are described above but also in the fact that they are no longer discouraged when their initial hypotheses is wrong, an outcome I had despaired of achieving!


  1. We started using this as our intro to scientific inquiry in both our Grade 9 academic and applied classes. It is simple to set up - anyone have any suggestions for another one that is simple and engaging like this one that we can use with our 10 applieds next year?

  2. Go to the Dollar Store and buy a bunch of compressed camping towels (8/$1). Student record dry mass. Slowly add water until towel cannot absorb anymore(saturated). Record volume of water added. Record final mass of towel.
    Density = [mass of water added (final mass - initial mass)] divided by volume of water added