stretch books seem quite interesting, defnitely worth a shot

Hi all. have a DS born in October. Was wondering wat u guys r doing to prep ur kid for streaming year next year. my kid has a lot to brush up on math. any reccs for enrichment centers/ assessment books?

Was recently introduced to stretch books by one of my friends. hearsay it is related to the textbooks my kid uses and is used by many high performing schools to train up math skills in their students. anyone got hear about these books before? any idea on where i can get my hands on them?