Lesson 2

To Get to the Other Side: Designing Bridges

Pushes and Pulls / Grade 2 / Arlington, MA

The EIE Curriculum

EiE - To Get to the Other Side: Designing Bridges, L2

Students think like civil engineers as they observe how forces affect structures and implement engineering solutions to balance forces and prevent structural failure.

Reflection Questions

Ann’s students have fairly sophisticated discussions throughout the lesson about forces, pushes, and pulls. How do you see her relating these discussions back to things they know and/or will be dealing with in the unit?

Ann gives specific examples of different types of forces and asks students to think about how they might affect bridges or other structures students are familiar with.

  • Ann asks students to think about the force of wind. A student explains that instead of pulling, like gravity, the wind pushes. Students will deal with pushing and pulling forces when they design their bridges. (2:36)
  • Ann asks students to think about the types of forces acting on a bridge. When she asks about piers, students are able to identify that the piers push up on and hold up the bridge. (3:08)
  • When talking about and later testing the one-story structure, students are able to apply vocabulary and talk about why the structure was successful (there was more force pushing up than pushing down, and therefore it did not collapse). (10:20)

When experimenting with the one story structure, Ann has students direct her where to put the weights. What affect do you see this having on the students?

Guiding students to think about where to add the weights helps them to make predictions about what might cause the structure to fail. 

  • When Ann asks students where to put the first weight, students comment on each other’s ideas and organically begin making predictions (it will fall down). Then when she does put on the first weight, students comment on whether their predictions were correct (I knew it, etc.). (8:00)
  • When adding more weight, students continue to make new suggestions and predictions, saying a weight should go on a certain pier or corner because it will balance other weights. (8:20)
  • When Ann later asks for a civil engineering solution to the problem, students are easily able to suggest putting a pier in the middle since they’ve been invested in previous testing. (9:30)