What are 'grow toys' made of? Why do they expand in water?

Subject: What are 'grow toys' made of? Why do they expand in water?

Date: Tue Mar 4 12:46:21 2008
Posted by Adam
Grade level: 7-9 School: No school entered.
City: No city entered. State/Province: No state entered. Country: No country entered.
Area of science: Engineering
ID: 1204659981.Eg

Message:


I've been wondering.  There are toys you can buy (at dollar stores, for example)
which grow (up to 600%, they say) when you put them in water. Often they are
shaped like dinosaurs, or sea creatures.  How do they work? What are they made
of?  What makes them grow in that way?  Thanks.

Re: What are 'grow toys' made of? Why do they expand in water?

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