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Upper El (11/30-12/4): Spy Week

This week, in the afternoons, was denoted as "spy week." Our weekly story prompt was "spy," we learned how to make invisible ink and write a coded message with a word cipher!

Our unit is chemical energy, and each week we've been exploring different products of chemical reactions. Last week we saw and felt heat-giving and heat-taking reactions. This week was about color change reactions.

Tuesday, we tested the pH of our creek water, tap water, and hose water, using strips that change color due to a chemical reaction. To all our surprise, the creek water was the perfect neutral of 7, while the hose and tap water were slightly acidic.

I posed the question if pH is the only indicator to consider when thinking of our drinking water? So, don't worry, no one is in any rush to take a sip from the creek!

We talked further about other uses for color change reactions, which led to the idea that we can write invisible messages!

Wednesday, that's just what we did. Students learned a simple recipe of baking soda and water to write invisible messages. Grape juice was our way to reveal them. After we got the hang of it, I asked them, "what are the shortcomings of invisible ink?" We arrived at the answer that if someone knows the recipe, they can still read our words! Not very good for spies.

I then gave each student two to three words to write in invisible ink, each getting a piece of a longer message. Then, they passed their few words to someone else in the class. Everyone revealed their words, and we wrote them on the board. They all put the pieces together to show the longer message: that tomorrow we will learn how to write in a secret code!

Thursday, not science, but a lot of fun, I taught everyone how to write using a word cipher. They all received a message I wrote, written using the cipher, and learned how to decode it. They then went off writing their own notes and using their own "keywords" for the cipher.

Friday, we finished up writing our weekly stories. Spy week was a lot of fun!

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