This is an easy-to-build picnic table sized for kids up to age 6 or so. I tried to keep it a standard size, with easy cuts and a simple structure. This is my first instructable, so suggestions are appreciated!

Step 1: Cut List

It's a short supply list:

8 Cedar 1" x 4" x 8' Deck Boards
75 Deck Screws (1 5/8")
Sandpaper and varnish or stain
Cut two trapezoidal seat supports, with the longer end at 33". Angle the ends at 22.5 degrees.
Cut two trapezoidal tabletop supports, with the longer end at 17". Angle the ends at 22.5 degrees.
Cut two center supports at 25.5" with square ends.
Cut four legs (parallelograms, if you'd like me to continue to be geometrically proper) at 21", again with 22.5 degree angles.
Cut nine 31" pieces for the table top and seats.

Step 2: Top Supports

Choose the best-looking top pieces that look good together and put them face-down on something soft. Align the ends and put the top supports and one of the spacers on as shown. Line everything up, put two screws in each end, then flip it over to attach the top.

Step 3: Top

Center and align the top center board and screw it down to the top support with two evenly-spaced screws at each end. Add the rest of the boards, spaced with nails, or tight against each other. (I made the first 10 or so with spaces, but as they age, I think tight against each other is better.)

Step 4: Legs

Line the legs up so that the outer edge of the leg is right near the bottom corner of the top support board and put four screws in from the inside. You might want to do two legs on a side first, then put one screw in each of the other legs in order to turn the table over and level it before putting in the remaining screws.

Step 5: Seat Supports

This spacing works well for me: with the table upside down, one scrap piece on end, one on its side, and screw the seat supports on. Make sure they're evenly spaced on each side.

Step 6: Lower Spacer

Put in the lower spacer with two screws from each end. I use 3" screws if I have any.

Step 7: Varnish

Put the Seats on to finish up, then sand as fine as you care to.

I'm in the Pacific Northwest, so it takes six coats of Varnish to make it two years, or you can let the table gray naturally. One thought about natural though - without the varnish, ketchup and mustard stains aren't very wipe-able.