Ninety-six children at several age levels from 6–13 years and 16 adults were asked to match handgrip force to length of lines and verbally presented numbers. Slopes of the matching functions increased with age, with the greatest differences in slope being found between 11–13 years on both tasks. Response variability was not a function of age, indicating that in spite of systematic differences among age levels, the method used has promise for the assessment of perceptual and cognitive skills of young children whose facility with the ratio properties of numbers cannot be assumed.