At the beginning of our Engineering Unit, we studied Towers – where the goal is to build a structure as tall as possible. In this session, we work to build a structure that’s as strong as possible. You can read the full Structures Lesson Plan here. In this post, I’ll just share some samples of materials we use in our buildings.
Toothpick Structures
For this method, you can use marshmallows or gum drops, grapes or cheese cubes. Kids can build as simple or complex as they like.

Interlocking Cardboard
By cutting slits in cardboard, you can create interlocking pieces that make much sturdier buildings than if you just stacked the cardboard. (You can also help your child notice how many building toys lock together in some way: Legos, Lincoln Logs….)
Fasteners
If you’ve built towers with cups, boxes, tubes, or blocks (as shown in our Towers post), you could demonstrate to the child how much sturdier their tower can be if they use fasteners such as tape, glue, binder clips, or string to attach items to each other. (You’ll want to remind them that they’re not allowed to glue things together without asking your permission first.)
Different shapes
Explore the idea that different shapes are sturdier. Try building some square columns and some round columns – which can hold more weight? Try adding an accordion folded layer into a building. Can it now hold more weight?
Strength Testing
You can test strength in a couple different ways. One is to return to the method from the Towers week of trying different methods to knock the building down. And every time you knock it down, you try re-building it stronger.
The other is the “how much weight can it hold” challenge. Try the index card bridge method or the binder clip and popsicle stick method.