Iowa State University



Earthquake CityTime: 20-30 minutesMaterials: Sugar cubes*reuse if possible*Jiggler cubesUnsharpened pencilsData sheet or paperCity layout gridCardboard base*reusable*Plastic knivesPencilsGetting Started:Discuss the movements of earthquakes and how they travel through the earth. Identify vocabulary such as “epicenter” and “waves.” Focus on how this movement will affect a city or a building.Directions:Divide the students into groups of 3. Make sure to give all instructions BEFORE distributing the sugar cubes. This will help them pay attention.Each group will need a cardboard base, city layout grid, 2 pencils, data sheet, and 15 sugar cubes. Pre-dividing the sugar cubes into piles of 15 will make distribution go faster.Part 1Tell the students that this is their chance to figure out the best way to design their city before the competition, so they will want to record their findings.Tell the students to set their cardboard base on the two pencils so that they support either side. Place the city layout on top of the cardboard. This will be their “city.”Give students 15 sugar cubes each. Build three sugar cube skyscrapersEach one needs to be five sugar cubes tall.Build the skyscrapers at the following corners:A and 1st B and 2nd C and 3rdTap on the corner of D and 4th with the eraser of a pencil. Continue to tap until at least one cube from each skyscraper falls.Questions to think about:Which skyscraper falls first? In a real earthquake, do you think more damage would happen in one place than another? Where would the most damage happen?Give them 5 minutes to experiment with different locations Determine how many hard or soft vibrations it takes to knock over buildings different distances away from the epicenter.Record results in a chart containing the location of the skyscraper and when it fell.Explain to them that in real life, the soil that the building is built on would play a big factor in the stability of the building. Some soils liquefy easily with vibration, causing the building’s foundation to virtually sink from under it.Discuss the materials used to build the skyscraper. What are some good things about the sugar cubes? Bad? Ask students how they think using another building material might change the outcomes.Give students 3 Jell-o cubes about 2” square – they can cut them down to the size they want. Remind them to be carefulGive the students 5 minutes to experiment with different materials to determine which combinations will work best for a building. Some materials (like steel) are flexible and can bend when a structure vibrates or moves, but some materials (like concrete) are stiff and brittle and cannot withstand much deflection with breaking. Engineers usually want a balance of these two properties.Ask the students what they could do with materials to balance out these two properties.A: Buildings and bridges are often designed using reinforced concrete. This consists of concrete with steel rebar (bars) inside of it. If a structure fails, the concrete will break, but the steel will flex and stop it from failing catastrophically.Part 2: Competition TimeHave the students use as many materials as possible from the research phase, and replace any materials that are destroyed so that they have the allotted number of materials for the completion.Rules:Students will have 7 minutes to build.Each group will get 15 sugar cubes and 5 Jell-o cubes (no replacements).Each group must design a city with at least 3 buildings.Each building must be at least as tall as the height of 3 sugar cubes.The group will designate the epicenter for the earthquake (circle it on the city grid) BEFORE they start building their city.Once the cities are complete, we’ll test how earthquake-resistant they are.Have one of the Student Role Models in charge of all of the tapping. When a team is ready to have their city tested, the designated person will tap on the predetermined epicenter. The presenter should record the number of taps, team name/students names on a master sheet. Stop the tapping as soon as a single block (of any material) falls.Any city that doesn’t fall down after 150 taps, will automatically be considered for the top prize. (There may be more than one prize winner if this is the case).DiscussionWhy is it useful to build skyscrapers out of different materials?Which materials were the best to use for taller buildings?Which cubes were the most earthquake resistant? Why?Which skyscrapers fell first in the earthquakes? Where were they located in respect to the epicenter of the earthquake?What happens when the top of a skyscraper is heavier than the bottom, or when the bottom is heavier than the top?What challenges did you face? (limited materials, limited time, team work) Discuss how these are issues that engineers face as well. ................
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