I developed a multi-agent framework 'Swimmy' (Squeak/Morphic), managed by Alan Kay and supported by IPA.

Swimmy Demo Image (Squeak 3.8 image and change file): Swimmy-Demo.zip

Please download Squeak 3.8 VM and run the image on that. 

Paper: Koji Yokokawa "Swimmy: A Framework of Multi-Agent Instruction System for Children" in IEEE the Third International Conference on Creating, Connecting and Collaborating through Computing (IEEE C5'05), pp. 27-32. (full text PDF)