About Construction by Instruction This classic activity develops spatial reasoning and mathematical communication. The instructions are self-explanatory. This activity can easily be offered without a volunteer to assist the children. Materials: all that is needed are two bags of duplos. The contents of the bags should be identical. Fifteen duplos in each bag in several different shapes and colors should do very well for the activity. Acknowledgements: Thank you to Yolande Haydon and Rita Brandenburg for the idea and for creating the original prototype for this activity. Written by Janet A. Dixon May 13, 2002