In order to get students attention and hook them into today's lesson, I begin by showing this video . This video is a video montage on the National Geographic website that shows earthquake damage. Prior to this lesson, my students learned that earthquakes have destructive and constructive forces. This video focuses on just destructive forces.
I begin this lesson by leading a class discussion about why we practice earthquake drills in school. I ask students to discuss how our school is safe and if they are aware of things in our schools like special earthquake proof windows. I remind students that because earthquakes can cause walls to crack, foundations to move and even entire buildings to crumple, engineers incorporate into their structural designs techniques that withstand damage from earthquake forces, for example, cross bracing, large bases and tapered geometry. Earthquake-proof buildings are intended to bend and sway with the motion of earthquakes, or are isolated from the movement by sliders. Engineers come up with an idea, test it, and then re-engineer the structure based on its performance.
Next, I tell students that today they are acting as if they are engineers. They will make models of buildings and conduct an experiment to test how well their structures stand up under the stress of an earthquake. I explain to them that this is similar to what some civil engineers do as their daily job.
I quickly show students how to how to make cubes and triangles using toothpicks and marshmallows. Show students how to break a toothpick approximately in half. Explain that cubes and triangles are like building blocks that may be stacked to make towers.
Next, I distribute 30 toothpicks and 30 marshmallows to each student. I tell students that the Earth has limited resources, so therefore engineers also have limited resources when building structures. I tell students that their structures should be at least 2 stories tall.
Student spend the next 25 minutes creating and building a structure.
You can see in these photographs students working together to build an earthquake proof building.
For this engineering challenge, students are limited to using only the materials they have been given to make structures. They may make large or small cubes or triangles by using full-size or broken toothpicks. They may use cross bracing to reinforce their structures. (Note: For higher grade levels, give students more rules for their buildings. You can use one or more of the following rules or create your own: buildings must be at least two toothpick levels high, buildings must contain at least one triangle, buildings must contain at least one square, or buildings must contain one triangle and square.
You can see in this video students building their structures.
After 25 minutes, I tell students that to test whether or not their building is earthquake proof, they will place their structure on a plan of jello and give the pan a shake. After 25 minutes about half of the student groups had a free standing structure and half did not. The groups that had structures standing informally test their structure. As groups test their structure, I ask students to notice shapes and characteristics of the structures. I remind students that tomorrow will be a redesign and retest day so noting differences between standing and non standing buildings is important.
To wrap up this lesson, I tell students that tomorrow they will have an opportunity to revise their structure in order to improve and enhance it. I tell students that engineers are constantly testing and redesigning.
Then I show this fun video as students clean up their areas. My fourth graders tend to like world records and often check out world record books from the library. This is a fun video that shows the worlds largest earthquake test.