The kids love edible math manipulatives, and this snack cracker worksheet that I quickly put together was a big hit in our homeschool. Just because Common Core doesn't cover area and perimeter until 3rd grade doesn't mean that Kindergarteners won't understand it..
I love the level of concentration that E put into her worksheet. First I asked the girls to estimate how many crackers will fit in each rectangle. I gave each one the number of crackers they guessed and if the estimate was too small, I asked how many more crackers we'd need. Then they calculated the area of each rectangle by counting the crackers. The girls measured the lengths of the sides of the rectangles using crackers and wrote down the number. I challenged them with questions about which sides might be the same length, etc.. Then we added up the lengths of the sides to find the perimeter. I showed them some tricks for faster calculation, like finding sums we know (2+3=5, and 5+5=10). I think that just like with reading last year, arithmetic concepts are finally clicking with the girls (after lots of repetition and hands-on activities).
UPDATE: I was so inspired by how much my kids enjoyed early math "games" that I created the La La Logic Critical Thinking Curriculum for 3-6 year olds, which includes online brain challenge games, printable worksheets, enrichment activities and more!