At DreamSpark Academy, summer is the perfect time to combine curiosity, creativity, and a dash of mystery! As part of our Summer of STEM series, students recently took part in a hands-on chemistry experiment that let them become secret agents for a day! They had the opportunity to write and reveal invisible ink messages using lemon juice and heat!
This classic activity not only thrilled our young scientists but also introduced them to the basic science behind chemical reactions and oxidation, using everyday materials they can find right at home.
What We Did
Each child received a cotton swab, a small cup of lemon juice (we used bottled juice), and a sheet of plain printer paper. Using the lemon juice as ink, students carefully wrote secret messages, initials, or doodles onto their paper. Once the writing dried and became invisible, it was time for the science to shine.
To reveal their messages, we used a heat gun to gently warm the paper, watching in amazement as the hidden writing appeared like magic!
Of course, there was a learning process involved. Sometimes the image was not dark enough and they had to use more juice. Sometimes they used too much and had to redraw their message or picture. Letting the students discuss what was right and wrong about their processes and make self-corrections was part of the fun.
Safety First!
Because this experiment involved high heat, we took special precautions to ensure safety. An extra teacher was on hand during the entire session to assist with heat gun use, and students were not allowed to operate or touch the heat gun themselves. Instead, students observed closely while a trained adult heated their papers one by one. Safety goggles were worn for good practice, and papers were handled with tongs to prevent burns.
Teaching children about safety around lab tools is just as important as teaching the science itself, and our team always makes sure that STEM is safe, structured, and fun.
What We Learned
This activity was a great way to introduce the concept of oxidation. Lemon juice is acidic and weakens the paper where it’s applied. When heat is added, those weakened areas oxidize faster than the surrounding paper, turning a light brown and revealing the secret message.
Students were fascinated to learn that:
- Chemical reactions happen all around us…even in the kitchen!
- Some messages can be hidden and revealed with the right tools.
- Science and creativity often go hand in hand.
STEM in Action
During the activity, students were encouraged to:
- Observe how lemon juice looked wet, then dried to become invisible
- Predict what would happen when heat was applied
- Experiment with different shapes and patterns
- Reflect on what other household materials could be used for invisible ink (hint: milk works too!)
Why We Love It
This experiment was a wonderful blend of science, storytelling, and safe exploration. It encouraged kids to express themselves while learning about chemistry in an age-appropriate, exciting way. Plus, it was a great opportunity to talk about how scientists use experiments to reveal things we can’t see with the naked eye. Additionally, it was great to see some students writing messages to their parents, or planning to try the experiment with them when they got home.
We believe STEM learning should spark imagination, and this activity certainly did!
Stay tuned for more Summer of STEM adventures as we continue exploring the wonders of science, one hands-on project at a time. Whether we’re floating ketchup packets or uncovering invisible messages, DreamSpark Academy is where curiosity takes center stage.