Working with manipulatives is an excellent way to build student math skills. Having a math center (or math rug) allows the students to collaborate and work together to solve problems via a worksheet or oral directions from the teacher. What I love about manipulatives is that they come in so many different shapes and sizes. I've seen teddy bears and farm animals, but my favorite would have to be DOGS.
The different colors can be used for making patterns or simply for doing basic math (adding, subtracting...etc..) If you are lucky, you might even be able to find the dog counters in different breeds to make the lessons more interesting.