Lesson plan Grade 6 Engineering & Design

Sable Ridge Water Tower Height and Stability Challenge

Teams design, build, and test a straw-and-tape model water tower across two rounds, meeting a height and load requirement for the fictional town of Sable Ridge.

Grade: Grade 6
Subject: Engineering & Design
Material: Lesson plan
Time: 55 min
Prep: Moderate prep
Materials: 20 plastic straws per team, 60 cm of masking tape per team (pre-measured and torn into small strips), 1 small paper cup per team (represents the tower's tank), 15 pennies or metal washers per team (for the load test), 1 metric ruler or meter stick per team, Scissors (optional, for trimming straws), A photograph of a real elevated water tower (for the hook)

Standards

MS-ETS1-1 NGSS

Define the criteria and constraints of a design problem with sufficient precision to ensure a successful solution, taking into account relevant scientific principles and potential impacts on people and the natural environment that may limit possible solutions.

How this material aligns: Teams must satisfy a stated 30-centimeter height minimum and a 15-penny load minimum within a fixed straw-and-tape budget before their tower counts as complete, defining criteria and constraints with real precision.

All materials for MS-ETS1-1 →

MS-ETS1-4 NGSS

Develop a model to generate data for iterative testing and modification of a proposed object, tool, or process such that an optimal design can be achieved.

How this material aligns: Round 1 and Round 2 generate height and load data that teams use to modify their tower design, the iterative testing and modification loop this standard describes directly.

All materials for MS-ETS1-4 →

6.EE.A.2 Common Core Math

Write, read, and evaluate expressions in which letters stand for numbers.

How this material aligns: Students evaluate the expression S = h + 2p for their own measured height and penny count in both rounds and on the exit ticket, substituting numbers for letters that stand for height and load.

All materials for 6.EE.A.2 →

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This material is in the public domain (CC0) and may be copied, edited, and shared freely, without attribution. Updated 2026-07-16.

Objectives

Students will state a minimum height and a minimum load requirement before designing a model water tower.
Students will build and test a straw tower across two rounds, revising their design between rounds.
Students will evaluate a design's score using the expression S = h + 2p, where h is height in centimeters and p is pennies held.

Vocabulary

Key words: stability, load, criteria, constraint, iterate

Teacher overview

The fictional water utility serving Sable Ridge has asked the class to model a new water tower before the real one is built, testing whether a tall, narrow support structure can hold a full tank without tipping or collapsing. Working in teams, students build a straw-and-tape tower that must reach a minimum height and hold a stated minimum load, then improve their design across two build-test rounds. A common misconception in this lesson is that a taller tower is automatically a better design; because each penny held adds 2 points while each centimeter adds only 1, an unstable tall tower can score lower than a shorter, stable one.

Procedure

Hook (5 min): Show a photograph of a real elevated water tank on a tall support tower and ask students why the tank sits so high above a wide, tapered base instead of a narrow one. Take two or three guesses without confirming an answer yet.

Direct instruction (10 min): State the design criteria and constraints: each team's tower must stand at least 30 centimeters tall, measured from the table to the bottom of the paper cup, and must hold at least 15 pennies placed one at a time into the cup without the tower collapsing or the cup falling off. Teams have a budget of 20 straws and 60 centimeters of tape. Introduce the scoring expression S = h + 2p, where h is the tower's final height in centimeters and p is the number of pennies it held before failing or reaching the 15-penny limit. Work a sample calculation as a class: a tower measuring 32 centimeters that holds 15 pennies scores S = 32 + 2 x 15 = 32 + 30 = 62 points.

Round 1 build (10 min): Teams construct their first tower design from straws and tape, aiming to meet both the height and load requirements within the straw and tape budget.

Round 1 test and record (5 min): Each team measures their tower's height with the ruler, then adds pennies to the cup one at a time, counting how many it holds before failure or reaching 15. Teams record their height, penny count, and score on the board.

Redesign discussion (5 min): Teams compare their Round 1 results with at least one other team's and identify one specific change to try, such as widening the base, adding diagonal bracing, or using fewer straws higher up where weight matters less.

Round 2 build and improve (10 min): Teams rebuild or modify their tower using their planned change, staying within the original straw and tape budget.

Round 2 test, record, and score (5 min): Teams repeat the height and load test, record their new height and penny count, and calculate their final score using S = h + 2p.

Closure and exit ticket (5 min): Students answer individually: "A team's final tower measures 28 centimeters and holds 12 pennies. What is that team's score using S = h + 2p?" Collect and scan responses before dismissal.

From Water for Schools (waterforschools.org). This material is in the public domain (CC0) and may be copied, edited, and shared freely.

Answer Key

Answer: 62 points. The sample tower's height (32 cm) plus twice its penny count (2 x 15 = 30) gives S = 32 + 30 = 62.
Exit ticket answer: 52 points. S = h + 2p = 28 + 2 x 12 = 28 + 24 = 52.
Discussion answer: A wider base spreads the supports farther apart, so the tower's center of gravity stays over its base even when it leans, which resists tipping, while diagonal bracing keeps the straws from folding sideways under the cup's weight; both changes usually raise the penny count more than they cost in height.

Differentiation

Support

Provide a simple triangular-brace diagram showing how two straws taped in an X pattern resist sideways folding, and let struggling teams start Round 1 by copying that base pattern before adding their own height.

Extension

Ask teams that exceed both requirements in Round 1 to redesign for maximum score using fewer than 15 straws, then explain in writing which straws they removed and why removing them did not reduce the tower's height or load capacity.

ELL supports

Pre-teach "stability," "load," "brace," and "collapse" using the photograph from the hook, pointing to the real tower's wide base and narrow supports while naming each part. Allow teams to record Round 1 and Round 2 results using the numbers and simple labeled sketches rather than full sentences.

Extensions

Have teams research, using only teacher-provided images, how a real elevated tank's shape (spherical, cylindrical with a cone bottom, or a standpipe) affects how much water it can hold, and compare that shape reasoning to the tradeoffs they discovered in their own straw tower design.