# Beaver Dam and Lodge Activity

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Carleton University
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Students build a beaver dam and lodge to understand what stable structures are and then they test their structure by placing a load on it - something heavy like a brick - and see if the force will make the structure collapse.

## What You Need

Introduction:

• 1 small bag of clay per student (enough to make 4 pieces the size of a mini marshmallow)
• Spaghetti (one whole piece per student)
• Toothpicks (4 per student)

Beaver Dam Building Materials (per student):

• Plastic clothespins
• 6 popsicle sticks
• 2 paper straws
• 1 chunk of clay (1 inch by 1 inch) in a baggie
• 1 12-inch piece of string
• A small handful of shredded paper in a plastic bag
• 10-15 small rocks
• Small rectangle metal pan

Materials that students/teachers will need to gather:

• Sticks from outside to make their beaver dam
• A piece of paper
• A pencil

## What To Do

1. At first, do a mini introduction to see what they already know about structures and forces. Ask them what structures are, what forces are. Then after they understand those concepts a little, talk to them about what kind of structures beavers build and what forces might act on those, emphasizing a triangle as a stable shape.
2. Then, show them a live example of what a beaver dam is like, so play this video from 11:39 - 13:12 to show them how a beaver dam is built. Then 18:17- 19:12 to show them the building of the beaver lodge. Then from 3:55 - 5:09 to show them how strong these beaver dam structures are. Video: https://www.youtube.com/watch?v=Ic3x8OVYe80&ab_channel=NationalGeographicKid
3. Then they design a dam and lodge on a piece of paper and are given the material to build it. They have to use the clothespin as teeth to build the material like beaver teeth but they can use their hands to pick up rocks and clay. If you see that the clothespins are too hard for them to use they can just use their hands.
4. They present their beaver dam and lodge and test it by putting a piece of brick on it and see how stable of a structure they built.

## Discovery

#### What's Happening?

What type of structure does a beaver build? [lodge and dam]. The dam makes it so the water is high enough on one side for the beavers, and the lodge is where the beaver lives and raises babies.

What is a structure? [one definition: "something that is built by putting parts together that has a function"].

What are some examples of structures that we see every day? [houses, garage, chair, table/desk, photo frame, malls, CN Tower, Eiffel Tower, play structure, etc.].

So you all agree that a chair is a structure right? What happens when we sit on a broken chair?

Structures have to be stable

An example of strong stable structure is a beaver dam

What is a force? A force is a push or pull on a load - load is any object that has been, needs to be or is to going to be moved. Push and pull forces.

Structures have a load - their own weight! An object's weight is how much we measure how much gravity is pulling on the object

A structure like a chair has to support its OWN weight before it can support you sitting on it.

A structure like a bridge has to support a lot of weight and that's why engineers make sure that they're really stable. Bridges resist natural forces like wind.