Chia Pets are terracotta figures of various shapes which are sold with seeds, which after soaking in water will adhere to the grooves in the figure and then germinate and become hairlike sprouts (over a period of a few days).
The Chia Seeds provided with the pet are 'Salvia Hispanica' of the Salvia genus (in the Mint Family). These seeds do not have the hallucinogenic properties of the Salvia Divinorum plant.
Chia Pets are suitable for a broad range of ages, from kindergarten (under supervision) through adult. Basically, you soak the figure in water, prepare the seed mixture and apply them to the figure, place it in its supplied plastic tray in the sunlight, and then watch it grow.
There are several properties which make the Chia Seeds well suited to their ornamental and experimental uses; among these are the seed's natural gelatinous nature and their high germination success rate (typically 98+% in reasonable conditions).
The same properties which make Chias good pets also make them a good tool for experiments and for demonstrating various physical properties.
In the Biology, Botany, and Chemistry areas, the Chia Pet can be used for experiments related to propagation, germination, and photosynthesis. Variables such as pH, salinity, amount and types of light, can be manipulated to test various hypotheses. The low cost and high success rate of the seeds make it very practical to have adequate control samples.
The seed's characteristics, make the gelatinous mass a good teaching opportunity for physical properties such as surface tension, density, and buoyancy.
For general science, Chia Pets can be used to teach the Scientific Method.
A variety of fun activities can be designed which will hold a young person's interest (What strange growth medium can you use to grow your Chia? Which team can keep their Chia alive the longest?, etc.).
Unlike some people, I don't eat the sprouts, but I like having the elephant around to look at (until he gets too smelly).
With the recent introduction of Chia Obama, and talk of a complete US President Series, in the future it may also be possible to use Chia Pets as a teaching tool for American History.
I have always had good experiences with Chia Pets.