Levers From Scrap Wood

I am a teacher of Secondary School and I teach Technology to 14-15 years old students. One of the lessons is Simple Machines and Mechanisms and it covers levers, pulleys and screws. After doing the written exam I noticed some of them didn't understand how levers work. So my idea was to build levers from scrap wood.

In Spain is usual to find strawberries in the market packed in wood boxes, so we could use this material and recycle it. This is an important issue, not to use expensive material and always try to reuse and recycle. Cardboard from packaging and scrap wood are always welcome!

Supplies

Wood fruit boxes

Screwdrivers

Pliers

Coins

Paper and pencil

Step 1: Getting Our Supplies

We only need some empty fruit boxes.

Using screwdrivers and pliers we can remove all the staples and get the different parts of the box.

The corners of the box are made with wooden wedges that would be perfect as fulcrums!

Step 2: Removing Staples

Although we didn't use them, I would recommend to use gloves in this step. We would prevent any harm caused while taking out the staples.

Step 3: Build Levers!

Here's the fun part, take one of the sides and balance it over the wedge. From one box we can build four levers because we have four fulcrums and four wood pieces.

Step 4: Balance the Lever

Without using a ruler we find the center of masses of the lever when it's balanced. Mark the position of the fulcrum using a pencil.

Step 5: The Law of the Lever

To use coins as weights is easy because we don't need a scale, simply use the same kind of coin in each side. Balance two coins in one side with one coin in the other one. Mark wher the fulcrum is and measure the distances with a ruler.

Let teenagers be creative and try different combinations. Balance the lever and mark the positon of the fulcrum. Repeat this process using as many coins as you like.

Step 6: Analyzing Results

Each pair of students have a work sheet that must be fulfilled with the results. I can tell it is not very accurate, but at least, they notice there is proportion between weight and distance, so the heaviest is the shortest side!

Step 7: Inclined Plane

As a plus, we can study inclined plane using these wood pieces and a dynamometer. Students would find some nuts and bolts to carry on the inclined plane and measure the different forces used.