Children have been found to be able to reason about quantitative relations, such as non- symbolic proportions, already by the age of 5 years. However, these studies utilize settings in which children were explicitly guided to notice the mathematical nature of the tasks. This study investigates children’s spontaneous recognition of quantitative relations on mathe- matically unspecified settings. Participants were 86 Finnish-speaking children, ages 5–8. Two video-recorded tasks, in which participants were not guided to notice the mathe- matical aspects, were used. The tasks could be completed in a number of ways, including by matching quantitative relations, numerosity, or other aspects. Participants’ matching strategies were analyzed with regard to the most mathematically advanced level utilized. There were substantial differences in participants’ use of quantitative relations, numerosity and other aspects in their matching strategies. The results of this novel experimental set- ting show that investigating children’s spontaneous recognition of quantitative relations provides novel insight into children’s mathematical thinking and furthers the understand- ing of how children recognize and utilize mathematical aspects when not explicitly guided to do so.