Choose storybooks that allow counting for kindergarten and early elementary students. You might choose books explicitly designed for counting or other books that easily lend themselves to counting.
Read the story aloud to the children first. On a second reading, begin guided questions, such as how many animals are there. Count together to practice the skill. Focus not just on the reading but on the illustrations as well, since these visual cues will deepen learning.
As children grow more comfortable with counting, look for opportunities to work in more advanced math concepts, such as simple equations and comparative vocabulary. For example, teach addition by adding together types of animals on each page or characters on one page with characters on another. Or ask questions such as, "Which is bigger, the lamb or the horse?" or "Which is smaller, the red balloon or the blue balloon?" The same can be done with other conceptual vocabulary, such as longer and shorter, older and younger or darker and lighter.
Write stories using your own equations. Teacher and students should do this together the first time. Soon students will be ready to write their own storybooks using their own equations or other math concepts.
Choose more advanced stories for more advanced students who are ready to grapple with more difficult reading material and more difficult math concepts.