Of Cabbages and Chemistry

Grades 4—8

Written by Jacqueline Barber

The humble cabbage has noble chemical merit. The juice from red cabbage turns pink when mixed with an acid, turns green when mixed with a base, and remains purple when mixed with a neutral substance. What a chemical canvas!

In this series of engaging activities, students use the special indicator properties of red cabbage juice to investigate acids and bases. Rather than starting with standard definitions, this unit plunges children into experiments through which they discover for themselves the distinction between the two, and their relationship to "neutral." The "Presto Change-O" activity reveals that acids and bases are parts of a continuum. Students also learn that chemicals can be grouped by behaviors, and these activities provide a great example of how closely chemistry connects to daily life. In a special assessment activity, students use their newfound knowledge to play a game in which they try to protect friendly visitors from outer space, who can only survive in a neutral environment.

Time: Four 60-minute or eight 30-minute sessions plus follow-up sessions.

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