This set of storytime ideas can be done with children who already know how to count, but want a little more math. For an activity, you could do many of the math or counting games available in lots of parenting/teacher books. Or, you could do a simple version of the African game Mancala, and practice counting in several languages in addition to English and Spanish.
Chorao, Kay. NUMBER ONE, NUMBER FUN. Farm animals dance, form pyramids, and do other activities while readers are invited to add and subtract them.
Slater, Teddy. STAY IN LINE. Twelve students are lined up in different formations while on a field trip to the zoo.
Larious, Julie. ON THE STAIRS. Mice count the steps on the stairs in this story with ordinal numbers.
Cristaldi, Kathryn. EVEN STEVEN AND ODD TODD. Steven likes even numbers, and has to adjust when his cousin Todd comes to visit. Of course, Todd likes odd numbers!
DeRubertis, Barbara. COUNT ON PABLO. Pablo helps count the vegetables at his grandmother’s market.
Schwartz, David. ONE BEYOND A MILLION. Get math trivia to spice up your storytime.
Also see Math storytime ideas from 2012.