Experiment of December 7, 2025:

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Solution video:

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Experiment:

Question:

What does Mr. Santa discover on the plate?

A) The coffee drop has dried and is evenly dark all over.

B) The coffee drop has dried. It is light in the centre and dark at the edges.

C) The coffee drop has dried. It is dark in the centre and light around the edges.

D) The coffee drop has dried. It is light on the inside and has dark, radial stripes.