If you were asked to list some strong materials you might think of steal, concrete, and wood. Would you believe that a piece of paper used correctly would support the full weight of a cinder block? Students will learn about the force of compression and how it acts on structural components through a hands-on group problem. Using everyday products such as paper, toothpicks, and tape they will construct a structure that will support the weight of a cinder block for 30 sec.

LEVEL OF DIFFICULTY [1 = Least Difficult : 5 = Most Difficult]

3- average

TIME REQUIRED

2 class periods (50 min each) 1/2 - 1 for discussion & background information. 1-11/2 for construction & testing of structures

COST

cinder blocks: $2-$3 each
student materials: $2 per class

Mass. Science & Technology / Engineering Grades 6-8 / Construction Technologies & Engineering Design
5.3 Explain how the forces of tension, compression, torsion, bending and shear affect the performance of bridges.
2 .2 Demonstrate methods of representing solutions to a design problem, e.g., sketches, orthographic projections, multiview drawings.
2 .4 Identify appropriate materials, tools, and machines needed to construct a prototype of a given engineering design.
2 .5 Explain how such design features as size, shape, weight, function and cost limitations (i.e., ergonomics) would affect the construction of a given prototype.

The students will gain insight into structural supports to withstand compression. They will develop construction skills. They will learn about the fundamental loads.

See Fairly Fundamental Facts about Forces.

Cinder blocks, can substitute text books
Per Group:
Piece of wood (smooth flat object to put the cinder blocks on)
(4) 3”x 5” index cards
(1) 8 1/2” x 11” copy paper
(1) 8 1/2” x 11” plastic transparency
12” masking tape
(15) Tooth picks (optional)
(2) Drinking straws (optional)
1 ruler
1 pair of scissors
3-4 pairs of safety glasses

Do the "Introduction to Loads on Structures" activity, to help increase what the students will be able to understand from doing the activity. Gather materials-setup a safe test area.

DIRECTIONS:

Problem Statement:
Using the material provided, teams of 3-4 will design and build a structure or structures to hold a concrete cinder block at a height of 3” above the floor for 30 seconds. More cinder blocks will then be added until their structure fails.

Students will have 10 minutes to brainstorm, during which time the students need to sketch their design ideas. When the time is up they will receive the materials. The maximum amount of time allowed to build the structure will be 15 minutes.

Testing will take place in the test area where all students are required to wear safety glasses. Each team will place their structure (s) on the floor and position the board onto their structure. Once in place two team members will slowly and carefully lower the block onto the board. Advise the students that they should be mindful of placing the cinderblock as flat as possible on the board to limit any twisting forces on their structure. Have the students, not placing the block; carefully watch their structure to see where and how it fails. After 30 seconds the solution will be deemed successful and more weight can be added until failure is achieved.

!!Warning!! Watch out for your fingers and feet during testing!

What is compression and what effect does it have on structures (structural elements)?
Give examples of compression, and find real life examples of structural elements that are in compression.
How did your structure fail?
Did it twist or slide to one side as it collapsed? If so what do you think caused your structure to fail this way?

REFERENCES:

None

WORKSHEETS:

See Associated Download.

SAMPLE RUBRIC:

See Associated Download.