Day 5: Chromatography
STEP 1: Before we begin any new investigations, it’s important that you understand how basic paper chromatography works. Watch the video below carefully—it shows exactly how to set up and run a chromatography test using simple materials like paper, water, and washable markers. Pay close attention to how the paper is cut, how the colors are applied, and how the paper is placed in the liquid. After watching, gather your materials and try the same setup. Don’t rush—make sure everything is placed just like in the video. This is your chance to practice the technique so you’re ready for the more advanced investigations we’ll do next.
STEP 2: You just watched paper chromatography in action—but now it’s your turn to figure out how it works. Before we move on, take a step back and ask yourself:
What’s actually making the colors separate?
- Is it something about:
- the chemicals in the pen ink
- the type of paper?
- the water or solvent?
- maybe it’s a mix of all three?
- or maybe something else entirely?
Turn and talk with a partner or small group.
Come up with a hypothesis: a smart guess about what’s happening and why the colors split apart and move up the paper.
Be ready to share your thinking with the class. We’re not looking for a “right” answer—we’re looking for curious scientists who notice, question, and wonder.
STEP 3: You made a hypothesis about how paper chromatography works—now it’s time to find out what’s actually going on!
Watch the video below carefully. This is the reveal moment. As you watch, ask yourself:
- What parts of my guess were right?
- What did I not know before?
- What new things did I learn about the pens, the ink, the paper, or the water?
Once the video is done, talk with your group again.
- What surprised you
- What makes more sense now?
- How does this explain what happened in your chromatography experiment?
We’ll come back together as a class to share what you noticed, what clicked, and what you’re still wondering.
STEP 4: Now that you know more about how paper chromatography works, it’s time to try the experiment again—but this time with a new set of pens. You’ll follow the exact same steps as before: use the same kind of paper, the same setup, and the same process. But pay close attention to how the ink behaves this time. Watch how the colors move—or don’t move—and think about what’s happening inside the pen ink based on what you learned from the video. Are the results the same as last time? Are the colors separating in the same way? After you run your tests, compare the results and talk with your group. What do you notice? What’s different? What can you now explain that you couldn’t before?
When you’re done, take a photo of your different pieces of filter paper side by side. Upload the photo and, in the “Write something…” area and include a short hypothesis about the chemical makeup of each pen based on what you observed. Use the QR code below to upload picture. Be sure to type your first name in the “Subject” line when you upload. Click here to see all posts.
