Water Dynamics – Get with the Flow!

Overview: Students will explore changing water levels by operating inflow and outflow mechanisms, graphing predictions, performing their experiments and graphing observations to test the accuracy of their hypotheses.

Lesson Objectives

Curriculum Context


 Students will be able to:

  • Use the characteristics of scientific thinking (observing, gathering information, looking for patterns, developing and testing possible explanations) to solve the problem of a changing water level.

  • Demonstrate that they understand the relationships of the inflow and outflow to the accumulation in a stock by creating and interpreting behavior-over-time graphs (BOTGs) while experimenting with water.

  • Apply the concepts learned in the science inquiry by making graphical predictions incorporating both the direction and the rate of change of the water level.


This lesson is appropriate for middle school (grades 6-8) science classes as it addresses the following science standards:

  • Identify a question, formulate a hypothesis, control and manipulate variables, devise experiments, predict outcomes, compare and analyze results, and defend conclusions.
  • Describe variables that cause change.

  • Create a model (e.g. a computer simulation or a stream table) to predict change.

  • Explain cause and effect of variable within a system.

  •  Identify characteristics of scientific ways of thinking, including: observing, communicating, comparing, organizing, relating, and inferring.

  •  Accumulation

  • Linear rates of change over time



Systems Tools

Per student group, a constructed water apparatus made of:

  • An empty, plastic two-liter bottle

  • A valve with a knob

  • Thread

  • Plumbers tape and caulking

  • A strong cutting device

  • A permanent marker

  • A ring stand

  • One gallon of water in a jug or plastic pitcher

  • A funnel

  • A plastic bin

  • A towel

  •  50-60 minutes

  •  Behavior-over-time graphs


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