Engineering with the Three Little Pigs - Part 2

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Objective

SWBAT explain how engineers need to consider material properties of rocks, soils and minerals when creating something new.

Big Idea

In this hands on building lesson, students act as engineers who figure out which materials are best for buildings they create.

Explore, Explain and Elaborate

40 minutes
Four days ago in a previous lesson students built four buildings.
Students will be watering premade bricks, balancing objects on pre-made bricks, and dropping bricks for this lesson to test the strength of different bricks made in a previous lesson.  Students will make observations about their bricks and conclude that engineers must make decisions based on a materials properties.  

For today's lesson students will complete part 2 - Testing

For this part of the lesson, I made sure that the B and C labeled buildings (filled bathroom cups) are completely dry. Next, I tell each table group to mix 2 bathroom cups full of sand with 6 tsp. of water in the bowl. I instruct students to fill the two remaining bathroom cups with this damp sand (no glue). Students mark an "A" on these cups.

Next, I instruct groups to take their two A, two B and two C cups inside a large metal bin.  Students also grab a brick and a watering can.  Have each team carefully turn over one of their A cups and place it in the metal bin.

Next, I direct students to slowly pull the cups off, leaving the damp sand. Then one student from each group will pour water on his/her building using the watering can. Students record what they observed. Did their buildings remain standing? What does the water from the watering can represent? (Answer: Rain or erosion.)

Next, each group sets up their second A building in the metal bin in the same way they did with the first one. This time they try and set the brick on top of the building. Ask the students what they observed and record in their science notebooks.  Is the building able to hold up the brick? What do they think the brick represents? (Answer: The brick represents the weight of people, furniture and other objects [loads] that the structure must hold up.

Next, students get one of their B buildings and place it on the ground. They tear away the cup from the sand, water and glue mixture very carefully.  Then one student from each group pours water on their B building using the watering can. Again, students record what they observed. Did the building remain standing? Did it hold up better or worse than the A buildings? Why did this building do better? (Answer: The glue helped hold the sand together.)  

Each group sets up their second B building in the metal bin in the same way they did with the first one. Have them try and set the brick on top of the building. Students record what they observed. Does the building hold up the brick?  

Next, for buildings that are still standing, have groups hold their bricks 6 inches above their buildings. On the count of 3, students drop a brick on each building. Students then describe their observations in their science notebooks. Students repeat the above procedures for each C building.  

 Listen in as these students talks about what happened to their bricks when water was poured on.

 

 

 

Evaluate

10 minutes

To end the lesson, I lead a discussion about how well the C buildings did compared to the A and the B buildings.  

I ask students to think about the situation if they had to live in a sand house: would they want live in a house like building A, B or C? Engineers also often must consider materials cost and other factors when building a house. Which of these buildings is the most expensive to build?

I discuss with students how engineers must constantly weigh the pros and cons of a particular design to come up with the best design. For example, we could build buildings out of titanium since it is incredibly strong; however, we do not actually build them out of titanium since it is so expensive and buildings do not need to be that strong in order for us to safely live in them.