Barnhill's Model Water Tower: Measuring Height in Inches

Opening demonstration (7 min). Show a photograph of a water tower or sketch one on the board.
Read aloud: "This tank sits up high. The water inside is heavy. It pushes down through the pipes and out of the taps below." Hold the plugged cup at desk level, pull the tape, and let the stream land in the tray. Then hold the same cup as high as you can reach and repeat. Ask what changed.

Setting the design problem (10 min). Lay the model street along a tray. Tell groups the tower must send water from the tank end to the far end of the street. Each group writes the design problem in one sentence and sketches a tower with the tank, the stand, and the street labeled. Require an arrow showing which way the water travels.

Building and testing (13 min). Groups plug the hole, fill the cup, set it on a stack of books, and pull the tape. They measure how far the water lands from the base of the stack, then add books and test again. Each group records two heights and two distances. Circulate and ask one question at each table: "What did you change, and what changed because of it?"

Measuring practice (12 min). Groups measure their own finished tower with a ruler and the model street with the measuring tape, then explain to a neighboring group why they used a different tool for each. This is the formative check: every group must give a reason tied to the length being measured, not to which tool was closer at hand.

Handout and closing (8 min). Students complete the six handout items independently. Close by asking the class how high a tower has to be to reach the end of the street, and take two answers that use a number from the day's testing.