Students learn how the force of water helps determine the size and shape of dams. They use clay to build models of four types of dams, and observe the force of the water against each type. They conclude by deciding which type of dam they, as Splash Engineering engineers, will design for Thirsty County.
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- Colorado: Science
- a. Analyze and interpret data identifying ways Earth's surface is constantly changing through a variety of processes and forces such as plate tectonics, erosion, deposition, solar influences, climate, and human activity (Grade 5)  ...show
- International Technology and Engineering Educators Association: Technology
- Next Generation Science Standards: Science
- Define a simple design problem reflecting a need or a want that includes specified criteria for success and constraints on materials, time, or cost. (Grades 3 - 5)  ...show
- Plan and carry out fair tests in which variables are controlled and failure points are considered to identify aspects of a model or prototype that can be improved. (Grades 3 - 5)  ...show
- Understand the concept of a force.
- Understand that water acts as a force on a dam and that the dam must respond with an equal force to hold back the water.
- Name four different types of dams.
- List some advantages and disadvantages of the different types of dams.
- water, 2 gallons (7.6 liters)
- 1 large waterproof bin, to catch any spilled water
- 4 small disposable plastic containers (available at grocery stores, or cut bottoms off milk jugs/ juice cartons, or use very thin Tupperware containers from a thrift store)
- scissors and/or hacksaw, for cutting plastic containers
- Four Types of Dams Worksheet, one per person
- course sand, 1 cup (play sand works, but tube sand or sand for concrete works best)
- plastic wrap, 1 x 12 in (2.5 x 30 cm) strip, for waterproofing; foil or paper also work
- 1 tsp (5 ml) modeling clay, for the spillway
- 10-15 small dominoes, wood or metal blocks (blocks should be close to domino size)
- 1 tsp (5 ml) modeling clay, for the spillway, to secure blocks, and as grout between blocks; can substitute tape and plastic wrap for clay
- modeling clay, one large handful
- modeling clay, half a handful
- 5 small (1-3 in, or 2.5-7.6 cm) dowel pieces (or straws or popsicle sticks), for dam support
- The most commonly-built type of dam in the U.S. is an embankment dam made of earth (also known as an earthen dam) and/or rock, which are readily-available and inexpensive materials. Its heavy weight and large size create the force to push back against the force of the water.
- Gravity dams are similar to embankment dams because they also use heavy weight and large size to exert enough force on the water, but gravity dams are made of concrete and considered more secure than embankment dams since concrete holds together well. Because so much concrete is needed to exert the force, gravity dams can be expensive. Gravity dams are often used in situations when extremely large dams are required and when the additional cost (compared to a less-expensive embankment dam) is deemed necessary due to people and property below the dam.
- An arch dam has a curved shape and is ideal for narrow, rocky locations. The shape of the curve takes advantage of the canyon walls. The curved dam redirects the force of the water into the canyon walls, reducing the need for heavy materials to hold back the water (as is done in gravity dams). This can make arch dams less expensive to build, but more expensive to design.
- A buttress dam supports the force of a reservoir through its bracing supports, called buttresses. The supports are designed like beams and, because they are directly in line with the force of water, redirect the force of the water into the stream bed where they are anchored. Buttress dams use less material than gravity dams, making them less expensive to build.
|arch dam:||A curved dam whose shape directs the force of the water into the canyon walls adjacent to the dam. This type of dam requires less material than any other type of dam and is ideally suited to narrow, rocky locations.|
|buttress dam:||A dam braced by a series of supports, or buttresses, on the downstream side. Most buttress dams are made of reinforced concrete.|
|dam:||A barrier to obstruct the flow of water, especially one made of earth, rock, masonry and/or concrete, built across a stream or river.|
|embankment dam:||A dam made of earth and/or rock, relying upon its heavy weight to resist the force of water. Embankment dams include a waterproof core that prevents water from seeping through it. Embankment dams are the most commonly-built type of dam in the US.|
|engineer:||A person who applies her/his understanding of science and mathematics to creating things for the benefit of humanity and our world.|
|force:||An outside influence that can cause a motion or pressure. For example, to open a door, you exert a force on the door in the direction that you want to open it.|
|gravity dam:||Massive dams that resist the thrust of water entirely by their own weight. Most gravity dams are expensive to build because they require so much concrete.|
|model:||(verb) To simulate, make or construct something to help visualize or learn about something else (a structure, an ecosystem, a process, etc.) that would be difficult or expensive to directly create or experiment on. (noun) A simplified representation of something, sometimes on a smaller scale.|
|spillway:||The route, channel or passageway through which surplus water escapes from a reservoir, so as to not damage the dam. A common spillway type is an overflow — a rounded crest that is somewhat lower than the top of the dam. The overflow allows water to be spilled from the reservoir before the dam overflows.|
Before the Activity
- Gather materials and make copies of the Four Types of Dams Worksheet.
- Make four "landscape" tubs by cutting one side off each of the four tubs per team.
With the Students
- Hand out the worksheet. Review with the students some details about each type of dam (see the Introduction/Motivation and Vocabulary/Definition sections).
- Divide the class into four groups (about 3-4 students per group), and assign each team a type of dam. For larger classes, if needed, assign more than one group the same dam type.
- Have each group create a design. This should include: 1) a list of the materials they will receive, 2) a drawing of the tub and their idea for their dam, and 3) dimensions of key features (such as the tub, dam length, dam thicknesses) and 4) all group members must sign the bottom of the design write-up. The teacher should initial when all four steps are complete.
- Have each team of students use the materials provided to build their type of dam. Remember the key concepts from each dam!
- For testing, direct students to place their entire model (plastic container and clay) into a waterproof bin so as to catch any leakage.
- Have students fill their small containers with water to test its force on their clay dam (see Figure 1). Wait one minute and record your observations. How is it working? Any leaks? Is the dam able to withstand the force of the water?
- Have students walk around the room to examine the dams created by other teams
- Have students complete the worksheet.
- Conclude by conducting a class discussion, comparing team experiences, and how forces are kept back by the different dam types.
- Make sure students clean up any spilled water so no one slips.
- Cutting plastic may be difficult, so be careful when using the scissors. A hacksaw works well for cutting plastic tubs.
- When engineers design a dam, what determines its size?
- Say you know how much water the reservoir needs to hold; now how do you determine the size of the dam?
Activity Embedded Assessment
- For lower grades, provide guidance to students drawing force arrows on the worksheets.
- For upper grades, have each team make a short presentation about their type of dam, including a demonstration using their clay model.
- For upper grades, have teams include a spillway as part of their clay model.
Additional Multimedia Support
Building Big: Dam Basics. WGBH Educational Foundation. Accessed December 4, 2007. (Good description and photos of four dam types) http://www.pbs.org/wgbh/buildingbig/dam/basics.html
Megan Podlogar, Sara Born, Kristin Field, Denali Lander, Lauren Cooper, Timothy M. Dittrich, Denise W. Carlson
© 2008 by Regents of the University of Colorado.
Integrated Teaching and Learning Program and Laboratory, University of Colorado Boulder
Last modified: October 12, 2015