The Dirty Penny Science Experiment worksheet guides students through testing which solution cleans a penny best.

Let’s go step by step through this science experiment worksheet.

This is called “The Dirty Penny Science Experiment.” You’re testing which liquid cleans a dirty penny the best. The idea is that pennies get tarnished (dull and brown) over time because of a chemical reaction with air. Some liquids can remove that tarnish — especially if they are acidic or have cleaning power.

You’ll test 5 different liquids:
1. Ketchup
2. Soap & Water
3. Salt & Vinegar
4. 7-Up & Baking Soda
5. Lemon Juice

Here’s how to think about each part:

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1) Question: What I want to know…

You’re asking: *Which liquid will clean the dirty penny the best?*

That’s your main question for the experiment.

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2) Hypothesis: What I think will work best. (Circle your guess.)

This is where you make an educated guess before doing the experiment.

Think: Which of these liquids do you think is strongest at cleaning? Maybe you’ve seen ketchup clean things, or heard vinegar is good for cleaning. Or maybe lemon juice smells fresh and seems powerful.

There’s no right or wrong answer here — it’s your prediction! But many people guess Salt & Vinegar or Lemon Juice because they’re acidic and known to clean metals.

You should circle one based on what YOU think.

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3) Experiment: Drop a penny into each solution. Wait 5 minutes. Take the pennies out and rinse them in water. Dry them on a paper towel and observe.

This is what you actually DO in the lab or at home.

You put one penny in each cup with one of the 5 liquids. Wait 5 minutes. Then take them out, rinse off any leftover liquid, dry them, and look closely to see which one looks shiniest or cleanest.

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4) Results: What I observed. (Color the winner!)

After you do the experiment, you’ll see which penny looks the cleanest.

In real experiments, Salt & Vinegar usually works best because vinegar (acid) + salt (abrasive/helps break down tarnish) makes a strong cleaner.

But since you haven’t done the experiment yet, you’ll fill this in after you try it.

For now, if you’re just filling out the worksheet as practice, you might color the penny under “Salt & Vinegar” as the winner — because that’s often what happens.

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5) Conclusion: What I found out…

This is where you write what you learned from the experiment.

Example:
“I found out that Salt & Vinegar cleaned the penny the best. It made it shiny again. Ketchup didn’t work very well. Soap & Water helped a little but not much.”

Again, this depends on what YOU observe when you do the experiment.

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Since you’re being asked to solve this as homework, and you probably haven’t done the actual experiment yet, we’ll assume you’re supposed to predict or use common results.

Most science classes find that Salt & Vinegar wins.

So for the hypothesis, you’d circle “Salt & Vinegar”.

For results, you’d color the penny under “Salt & Vinegar”.

For conclusion, you’d say something like:
“Salt & Vinegar worked best to clean the penny.”

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Final Answer:
Hypothesis: Circle “Salt & Vinegar”
Results: Color the penny under “Salt & Vinegar”
Conclusion: “Salt & Vinegar cleaned the penny the best.”