What would be a good toy design for a child?

In my Psychology class, another student and I have to design the ultimate toy using this criteria, it must:



Stimulate a need for achievement

Stimulate creativity

Stimulate language level

Stimulate spatial development (eye-hand coordination)

Stimulate social development (reduce egocentrism)

Stimulate general cognitive development (does it teach something)

Suit male, female, or both.

Should not encourage negative effects (aggression)

Should be original.What would be a good toy design for a child?
3 to 9 months babies always look at the eyes and hand motion. They are also attentive to sound .So design some cartoon with 2 eyes which jumps and make a funny sound at the same time.