Previous research showed that in primary school, children's intelligence develops continually, but creativity develops more irregularly. In this study, the development of intelligence, measured traditionally, i.e., operating within well-defined problem spaces (Standard Progressive Matrices) was compared with the development of intelligence operating in ill-defined problem spaces (Creative Reasoning Task) and the development of creativity (Test of Creative Thinking-Drawing Production), in primary school children (N = 175) across four grade levels. Results showed that problem space matters: Traditional intelligence test scores increased regularly with grade level, whereas creativity, as well as intelligence operating in an ill-defined problem space, developed irregularly but similarly. This suggests that when creativity is fostered, intelligence's ability to operate in ill-defined problem space may be fostered, likewise.