The use of unifying themes that span the various branches of science is recommended to enhance curricular coherence in science instruction. Conceptions of spatial scale are one such unifying theme. This research explored the accuracy of spatial scale conceptions of science phenomena across a spectrum of 215 participants: fifth grade, seventh grade, ninth grade, twelfth grade, and doctoral students in science. Conceptions spanning sizes from one nanometer to one billion meters were investigated through use of written assessments and individual interviews. Results showed that accuracy of conceptions at small scale were not symmetrical with respect to conceptions at large scale. Large scale accuracy tended to decline in a smooth, uniform fashion as the scale increased, whereas small scale accuracy displayed a discontinuity at the microscopic level. To conceptually interact with scales far removed from human scale, experts used strategies of mentally jumping to a new scale-world. Experts tended not to transition smoothly between the differently scaled worlds but rather to make a discontinuous leap, maintaining abstract linkages between the worlds via mathematics. Implications of these findings for curriculum development and classroom instruction are discussed.