Got a second grader going into third grade? More than likely, they've already been introduced  to the concept of multiplication. To keep the concept from "washing away with the tide like a sand castle", use this beachy fun Read, Draw, Write resource to firm up their understanding of multiplication as equal groups. Teachers...this would be a nice little packet to send home with the kids for the summer.
 https://www.teacherspayteachers.com/Product/Tidal-Times-Multiplication-Concept-and-Facts-Read-Draw-Write-1343358