Knowledge of acids and bases doesn't need to be a secret. Learners use red cabbage to create an indicator solution, then test how adding lemon juice (acid) and detergent (base) changes the color of the solution. They then use the concept to write secret messages.

Concepts

color, detergents, acids and bases, indicators

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Instructional Ideas

• Have the class test the acidity of different materials
  

Classroom Considerations

• Familiarity with acids and bases is advantageous
• Requires red cabbage, lemon juice, detergent, and other basic materials
  

Pros

• Pictures in the instructions help show the process
  
• Worksheet can be downloaded and printed if necessary
  

Cons

• Scholars may be confused by references to vinegar and ammonia, given that these substances are not used in the experiment