Water Filter

Act 1:

How long will the filter last?

Act 2:

What information would be useful to figure this out?

Initial Flush


The students need to know the capacity of the filter and the fact that 3 gallons need to be flushed through before use. Also, average water consumption would be useful to know. In order to provide this, I decided to collect data for a 1 week period at the beginning of the filter’s life.

Water Consumption.psd

I’m excited about this because the students can figure out an average consumption in multiple ways. Should average daily consumption be calculated? Weekly? Monthly? Students can decide based on what they are most comfortable with. Also, they will have to decide how to use the information. What does the number of glasses help us with? How can we use that information based on the units given on the label (liters and gallons)? I provided the glass dimensions to help answer this question (see the official lesson page).

Act 3:

I replaced the filter a few days ago so the answer isn’t available yet. However, I think this could actually make the task more interesting. Instead of seeing the real answer, the students can make predictions and write a letter advising me when to purchase a new filter…


When should I purchase a new filter? Write a letter to advise me.

Students can submit this letter as a final report, and I’m excited to see their reasoning. Not only will tables, graphs, and equations be persuasive, but other reasoning such as shipping times and product availability will come into play.

Lesson Page:

What are your thoughts? How can this be improved?

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