Write in invisible ink

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Write in invisible ink
Age Range 5-8 (grades 1-2), 8-11 (grades 3-5), 11-14 (grades 6-8)
Group Size medium (6-20)
Setting indoors
Setup Time medium (6-30 min)
Duration medium (11-30 min)
Subjects chemistry
Key terms catalyst
Materials 3 bowls, milk, paint brushes (variety of small sizes), q-tips, white paper, heat source (stovetop burner, 100 watt light bulb- not halogen, iron), oven mitt or towel
Presentation Style demonstration, interactive

Brief Description

Students get to create invisible ink and write with it!

This Is How You Play

  1. Tell children that they are making secret messages with invisible ink. They are to draw or write a message to a family member or friend. Let them know not to use too much milk, or else they won’t be able to see what is on their page.
  2. Divide the children up into 3 groups of 4.
  3. Give each child a piece of paper. Have a stack of extra paper handy.
  4. Pour a small amount of milk into 3 bowls and hand them out to each group at a table.
  5. Give each group a variety of different paint brushes and Q-tips; at least 1 per child.
  6. Make secret messages.
  7. Set aside to let dry.
  8. When dry, use some kind of heat source to make the message "appear."

NOTE: Do NOT put paper directly on any heat source. If using a burner or 100 watt light bulb use the oven mitt or towel to hold the paper above the source so it does not catch fire, but is still close enough to feel the effects of the heat. If using an iron, place the paper on a flat surface, cover it with a towel, and then place the iron over it.

Why this works: Milk blends in with the white paper when it is first applied. When heat is added the sugars in the milk begin to cook, producing a change in color from white to brown.


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