Summer squash have edible thin skins and soft seeds. Zucchini, pattypan and yellow are the most common varieties. Choose firm summer squash with brightly colored skin that's free from spots and bruises. Generally, the smaller the squash, the more tender it will be. Refrigerate summer squash in a plastic bag for up to 5 days. Before using, wash squash and trim both ends. If using sliced summer squash in salads or stir-fries, blot dry with a paper towel. One pound summer squash equals about 3 medium or 2-1/2 cups chopped.