There is a wide variety of excellent children's books available to stimulate interest in both math and science. I have picked three of my personal favorites.
Everyone Poops by the renowned Japanese children's author, Taro Gomi, is so popular that it has published in the United States as part of the series "My Body Science". Briefly, it acknowledges that all creatures participate in the process whereby their bodies eliminate waste from their system. While it may be viewed by some as a "potty training" primer, it actually relates a much deeper meaning. It can be used to show that all life is interconnected. Whether that lifeform is fish, insect, fowl, or human we all share necessary life functions. In order to prevent the possibility of having the students actually interacting with feces, activities would best be applied to how poop is dealt with once it leaves the body. This could be accomplished by a variety of field trips. You could visit a pet store and view the plethora of products available for dealing with your pet's output. You could make posters showing the products that humans use for their personal hygiene. Maybe, you could even visit a waste treatment plant.
Go, Dog, Go by P. D. Eastman is a wonderful book to show children the concepts of mechanics. While it may use dogs to illustrate these concepts, the activities are common to all walks of life. Up vs. down, in vs. out, over vs. under - all are scientific terms used to define placement. An added bonus is the concept of rudimentary counting. A short play would be an excellent way to illustrate the myriad of positions in which the dog's find themselves. This would incorporate the use of wedges, levers, hoists, etc.
The Very Hungry Caterpillar by Eric Carle may be a simple picture book, but it speaks volumes. It beautifully illustrates metamorphosis. It teaches that living things do not start out as they end up. Caterpillars become pupae and finally butterflies. One obvious activity would be to grow some butterflies (thebutterflysite, insectlore, ordercaterpillars,etc.). However, you could also grow plants from seeds, or discuss the various stages of human development.