Graphomotor skills involves coordinated participation of perceptual, cognitive and motor mechanisms. Our interest is related to children's ability to draw circles of different sizes in an increasing order (the seriation task). Two additional control tasks have also been realized, the first one with the circles in a random order, the second one with the circles assembled in such a way that they represent a bear. We have studied children from 5 to 9 years and adults. The major results for the seriation task are the following: model sizes have always been underestimated (highest underestimation at 7 years, lowest at 9 years). Mean size increment decreased between 5 and 8 years and increased between 8 and 9 years. The average velocity decrease between 5 and 7 years, followed by a regular increase between 7 and 9 years, the lowest average velocity at 7 years, the highest at 5 years. Whereas the 5-year-old children (like adults) execute the task by means of an automatized mode of functioning (highest velocity, low size accuracy, best circle size increment value, optimal covariation size-velocity, but also highest variability), children from 6 to 9 years are using a controlled mode of functioning (increasing size accuracy, low velocity, reduced size increment, slightly reduced covariation size-velocity, but decreasing variability).