Formal climate education without consideration of the ocean is incomplete. The effectiveness of a new climate lesson for youth that includes the ocean-climate nexus was examined by delivering the lesson to nine classes situated in separate British Columbia, Canada public schools and assessing the students' understanding of basic climate concepts before and after the lesson. Among the youth assessed, before-lesson understanding of basic climate science concepts was low. The lesson led to significant improvements in the understanding of climate science; the after-lesson level of understanding appears to be a function of age. The classes with the lowest (29%) and highest (73-79%) after-lesson class averages were the classes composed of the youngest and oldest students, respectively. The age-related differences are considered with respect to the students' cognitive developmental stage, and suggestions are made to improve understanding among younger students.