I taught kindergarten for three years, and a big part of math and science at that level is "sorting and classifying." It's just a fancy term for separating a group of objects into likenesses and differences - like sorting stuffed animals into dogs, bears, cats, etc. We had a tub of what's called "pattern blocks," colored wooden or plastic triangles, rectangles, squares, etc., and the kids would sort them by color, or by shape, or by three sides, four sides, and six sides. Children in the early childhood years love sorting and classifying.
You can create opportunities for your kids to practice this at home quite easily. Tons of stuff around your house can be sorted. Stuffed animals, as I mentioned. How about a box of pasta that's lots of different shapes mixed together? Or you can save bread wrapper tags - those plastic things that hold the wrapper closed - till you have a good collection. They can be sorted by color, shape of the hole, types of corners. Got a junk drawer? (Who doesn't?) How about all those pens and pencils? They can be sorted into pens and pencils, including mechanical pencils, or ones that write and those that don't, or by color of ink, erasers that work and don't. (Got an idea of what my junk drawer looks like?) I also have a pile of rubber bands that I've collected from the mail and the produce department at the grocery store. There are lots of ways to sort them - size, color, width. Sometimes at the craft store, you can buy a bag of buttons. Those are really fun to sort - by number of holes, color, size, smooth or textured, round or not.
Got the idea? Give it a try! I promise once your kids catch on, they'll love it!