The goal of this paper is to account for the fact that children acquiring English from different linguistic backgrounds (Spanish, French, Korean, Russian and Bantu languages) often produce sequences in which they omit the verbal inflection, and in which they insert is. Children's production of sequences with inserted is is interesting for two main reasons: firstly, utterances like these do not occur in the input (adult English); and secondly, children's insertion of is adheres to a systematic pattern. As for what motivates children to produce sequences with is-insertion, I link this to a language learning strategy. During the course of English acquisition, and independently of children's L1, learners have access to two types of information: lexical and syntactical. While the uninflected verbal form (base verb form) carries the lexical information, the be forms ('m, is, are, was, were) inserted in a sequence, provides learners syntactical information. I argue that children's choice of is-insertion over verb movement is a more economical option for learners of English as a second language. Crosslinguistic support for this proposal is provided.