Time and the expression of time are integral features of all cultures and languages. When we learn our first language, we learn not just the language to talk about time but also how to express our perceptions of time. These perceptions are often at the subconscious level. The current paper contrasts the expression of time in both English and Arabic not just from the grammatical perspective but also from the semantic. Learners bring this intuitive understanding of the expression of time through tense and aspect from the first language (L1) and it is argued that this affects all subsequent language learning. An analysis, not just of the grammatical differences but also the meaning and functional contrasts, can help understand why our learners make the errors they do and can also inform material developers so that learner texts can take these differences and challenges into consideration.