Preparation

1. Have a parent or sibling write a secret note with one of the black markers on the coffee filter. Make sure your student scientist doesn’t see which marker was used!

2. Use tape and Sharpie to label each type of marker with a number for easy organization and identification.

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Experiment​

1. Cut up your coffee filter 3-4 into long 1-inch strips

2. Cut a strip from the ransom note that includes some of the writing. 

3. Draw a medium-sized dot at the bottom of each strip using the different markers you chose for each. 

4. Make a note of which marker you used for each strip

5. Tape each of the strips to your popsicle stick such that they don’t touch. Make sure each strip will fit inside your cup without touching the bottom. 

6. Fill your cups with water until the bottom edge of the filter strips are just touching the water. The dots you drew should still be above the water level.

7. Wait and observe as the water moves up the strips! (5 mins)

8. Compare the colors of your resulting patterns with those from the ransom note to determine which marker the thief used to write the note!

9. Clean up!