I needed some 3 inch squares cut from 1/4 inch plywood. I had access to a Black & Decker Workmate and a circular handsaw, but not to a table saw or a radial arm saw. Cutting small pieces like that can be dangerous with a circular saw because it is difficult to secure the wood and things can get out of control very soon. I used my Workmate both to secure the wood and to guide the saw safely.
This is some scrap 1/4 inch plywood. Neither of the two edges visible is straight and true. I used my tri-square to mark a straight line so I can trim the plywood for a true edge. See this Instructable to make this tri-square