<p>Verbal Probability Expressions (VPEs), such as “likely” or “rarely,” are often used to communicate scientific information that is uncertain and are often preferred over numerical expressions despite a higher risk of misinterpretation (mode preference paradox). Prior research has focused on adult interpretations of VPEs, with only few studies focusing on how young people understand them. This study investigates how secondary school students in England interpret 29 common VPEs using a slider-based scale (0–100%) by use of an online questionnaire. Our sample included 184 students in two age groups to compare differences between lower and upper secondary school, an age when linguistic repertoires become increasingly formal and aligned with disciplinary language. Results show that VPEs indicating extreme certainty or moderate probability elicited the most variability, while those near 50% or suggesting low probability showed greater agreement. Older students demonstrated more consistent and polarized interpretations, a trend strengthened when comparing our data with that of adult audiences. No gender differences were observed in our sample. The study concludes by suggesting a framework for benchmarking VPEs that can be used in future research, in educational practice and in communicating science for secondary school students. It also expands understanding of how VPEs develop with age.</p>