The possibilities of 5-years-old children's training to use combinatorial skills on multi-loop object and to analyze several factors' interaction in it are studied. The method of training and control of this activity mastering is offered. It is based on the use of special technical devices - puzzles' complex. Trained preschoolers when experimenting with a new multi-loop object by themselves find such its sides which were not shown to them and which their un-trained peers cannot find.