Penny Lab

Penny for your thoughts? If you are looking for hands on, easy to work with materials that can span across subject areas, we have the answer… check your spare change jar. Pennies are not just coins to collect in a jar; they can be tools for learning, science experiments, and even engineering challenges. They’re easy to keep on hand, they go a long way without taking up a lot of space, and there are all sorts of opportunities to learn! So let’s invest in learning with Penny Labs!

No Prep Penny STEM Challenges

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Before we dive into all the cool activities you can do with pennies, there is a big elephant in the room… many of you live in countries that don’t have pennies anymore (or the equivalent low denomination coins). Canada, Finland, the Netherlands, Sweden, Australia and New Zealand are just a few of the many countries that have done away with pennies. But this list is not exhaustive, there are many more around the world.

But don’t fret! You can still do most of these challenges. Simply use whatever coins you have available.

Below we have fun facts about the American penny. For fun facts about your own local currencies, challenge your students to do some research and see how your coins compare to American coins.

The key with these challenges is that they are quick, easy and they simply use coins from our coin jars! Making them perfect for some quick activity ideas for the kids.

Penny STEM Challenges

Pennies are perfect for hands-on activities that teach STEM concepts. These hands-on challenges are low to no prep and an easy filler project for those days when you need something quick! 

Build a Penny Bridge

We don’t expect the bridge to hold any weight, but it will need to have two sides at least an inch apart and the top will need to completely connect the two sides without falling over.  

Want more bridge ideas? Check out Rainbow Bridge Challenge and da Vinci Bridge Building.

Give each student or group about 50 pennies. They can build a bridge with way less but that’s a good amount to have on hand so they can experiment with some trial and error. 

First step with any STEM challenge is to talk it out or brainstorm!  Important questions and considerations:  What are you going to need to do in order to make sure your pennies don’t fall? How can you connect the sides without just collapsing?  How high should the sides be? Does it matter?  

Take notes and maybe sketch out some design ideas.

As they build, remind students to think about how engineers design real bridges to distribute weight and handle heavy loads. Encourage them to experiment with different shapes and supports to make the bridge stronger and more stable.

This challenge will have a lot of trial and error because the pennies will slide around and topple, but in the end it is possible and such a fun challenge.  

Penny Tower Challenge

How Many Pennies Can You Stack Before They Fall Over?

The kids really get into this little competition.  They may think that as long as their piles are neat and straight they can stack as high as they want but in the end gravity will take over and topple the pile every time. 

Why?

It’s a concept known as the center of gravity.  NASA says “The center of gravity is a geometric property of any object. The center of gravity is the average location of the weight of an object.”  

The entire stack acts as if its weight were located only at the center of gravity!  This puts the center of gravity about in the middle of the stack.  So as the pile gets higher the center gets higher, and since the lower the center of gravity is – the more stable it is – then it  stands to reason that the higher the center gets, the more unstable the pile is. 

You also need to take into account are the pennies perfect? Are they worn? You should be able to build a higher stack with pennies from more current years because theoretically they will be more uniform in shape and have less overall wear. 

Penny Math

How Much Does a Penny Weigh?

Have you ever wondered how much a penny weighs? The weight of a modern American penny is 2.5 grams. You can use a scale to weigh your local currency to see how it compares. Then give some of these math challenges a go!

How Much Does 100 Dollars Worth of Pennies Weigh?

Step 1: First, calculate how many pennies are in $100. Since each penny is worth one cent, and there are 100 cents in a dollar, you’ll need to multiply: 100 dollars×100 pennies per dollar=10,000 pennies.

Step 2: Now, multiply the number of pennies (10,000) by the weight of each penny (2.5 grams). 10,000 pennies×2.5 grams per penny=25,000 grams.

Step 3: Convert grams to kilograms (since 1,000 grams equals 1 kilogram): 25,000 grams÷1,000=25 kilograms.

So, $100 worth of pennies weighs 25 kilograms that’s over 55 pounds!

How Much Does 1 Million Pennies Weigh?

Let’s take things to the next level with another math challenge: What if you had 1 million pennies? You would be RICH! But wait… would you really? Or would you get squashed by the weight of all those coins? Let’s calculate the numbers.

Step 1: First, convert 1 million pennies into dollars: 1,000,000 pennies÷100=10,000 dollars. So, 1 million pennies equals $10,000.

Step 2: How much do all of those pennies weigh? Since each penny weighs 2.5 grams, multiply the number of pennies by the weight of one penny:  1,000,000 pennies×2.5 grams per penny=2,500,000 grams.

Step 3: Convert grams to kilograms: 2,500,000 grams÷1,000=2,500 kilograms.

That’s 2,500 kilograms or about 5,511 pounds as much as a small elephant or a truck!

More Penny Math Ideas

If you’re working with kids starting out with multiplication, penny stacks are a great way to build competencies. Start by building stacks of pennies with the same number of pennies in each stack. Then have kids count by the number of pennies in each pile.  10 pennies x 10 stacks = 100 pennies.  

I also love to do penny timelines , it works one on one or with a group.  Have kids check the dates on pennies and put them in a numerical timeline.  When working with groups or teams give each a pile of pennies and then have them negotiate trades with other groups for holes in their timelines!  The pennies are a great math manipulative. There are so many possibilities.   

Penny Science

What are Pennies Made of?

Pennies haven’t always been made the same way in the United States and this is true around the world. The minting or process of making coins has changed and evolved around the world through the years.

In the USA the modern penny is made mostly of zinc, with a thin coating of copper but that wasn’t always the case.  

Before 1982: Pennies were made of 95% copper and 5% zinc.

After 1982: Pennies were changed to 97.5% zinc and 2.5% copper. This change was made because copper became more expensive, so using zinc helped save money.

How to Clean Pennies?

Over time, pennies can get dirty and lose their shine. They will sometimes develop a green patina or coating on the coins.  It happens because there is a chemical reaction between the copper and oxygen that is called oxidation.  It’s the same thing that makes the Statue of Liberty in New York appear green and it actually helps to protect the copper.  

We can use another chemical reaction to clean pennies.  You can use lemon juice or vinegar plus salt. To make this a true experiment, try them side-by-side and have the students compare the results.  

Try this simple penny cleaning experiment.

Materials

• Dirty pennies
• Vinegar or lemon juice
• Salt
• 2 Small bowls
• Paper towels or a cloth

Directions

Set out two bowls. Label one Vinegar and one Lemon Juice.

Mix a teaspoon of salt with a half cup of vinegar in the vinegar bowl. Then do the same with salt and lemon juice in the same amounts in the Lemon Juice bowl.  

Drop the dirty pennies into the solution and let them soak for about 5 minutes.

Remove the pennies and wipe them with a cloth. Watch how the grime comes off, revealing shiny pennies underneath!

The acid in the vinegar or lemon juice reacts with the copper oxide (the tarnish on the pennies) and dissolves it, leaving the pennies clean and bright. But why use salt? Salt is Sodium Chloride and it penetrates the oxide layer allowing the acid to reach the copper resulting in a better cleaning of the coins.

History of the American Penny

Pennies lead the way to some fun conversations and research opportunities. Who is on the US Penny? What is he known for? Has the penny always looked the same? How are pennies produced or minted? Where?  There are tons of opportunities to pull pennies into the conversation!

How much Does it Cost to Make a Penny?

Did you know, it actually costs more than one cent to make a penny! Recent estimates say it costs about 2.1 cents to produce a single penny. Why? There are lots of factors like, the cost of materials, manufacturing costs, and distribution costs as well. That means that every penny made is produced at a small loss to the U.S. Mint. This expense is a big reason why many countries have stopped making pennies, it is simply too expensive.

Fun Penny Facts

• The first U.S. penny was minted in 1793.
• Abraham Lincoln’s face has been on the penny since 1909.
• More than 300 billion pennies have been minted since 1787!

Pennies may be small, but they open the door to big learning opportunities, there is definitely no shortage of educational opportunities packed into these little coins. So the old adage holds true – find a penny, pick it up and all day long you’ll have good luck – and lots of fun stuff to learn as well!