One thing that I always enjoy teaching to preschoolers is sorting objects. We've found that using inexpensive items that we have around the house works best. My 3 year old and I use a collection of bottle caps we have to sort by color and size. We began with a simple A,B pattern (red, blue, red, blue). Next we added an AA, BB pattern (red, red, blue, blue). From there the patterns just kept getting more elaborate; A,A,B and A,B,B,C, etc. We had so much fun with this activity. For days he was noticing patterns everywhere we went. Another golden opportunity seized!