Seesaws, also called teeter totters, are a common sight at public playgrounds. Children sit on either side of a see-saw and play by bouncing each other into the air. Seesaws help teach children about simple machines and how leverage can help us lift heavy objects. Children can also discover how a heavier child can balance with a smaller child by moving closer to the middle of the see-saw. Commercially-made seesaws are usually constructed from plastic or metal. You can make a see-saw that will primarily use wood.
Cut the 3 inch by 1 inch board into four sections 20 inches long each and one section 13 inches long. There should be approximately 3 inches remaining.
Lay the five boards out on the ground or work surface so that they form an "H" with the 20 inch boards as the vertical lines and the 13 inch board as the cross piece. The 13 inch board should be sandwiched between the 20 inch boards. The bottom edge of the 13 inch board should be 4 inches from the bottom of the 20 inch boards.
Bolt the boards together by drilling a ½ inch hole through the centre of the area where the boards meet. Each side gets one bolt. Secure each bolt in to place by holding the head of the bolt with one wrench while tightening the nut with another wrench.
Drill another set of ½ inch holes so that they are 3 inches from the top edge of the 20 inch boards. Insert secure bolts into these holes and lightly tighten the nuts. There should be 1 inch of exposed bolt between the 20 inch boards.
Line the bottom of the tire with a thick trash bag to prevent concrete from pouring out of the bottom hole. Make sure that the bag has no holes and completely covers the tyre's bottom opening.
Position the wooden "H" so that it stands vertically in the centre of the tyre's hole. The 13 inch cross piece should be close to the top of the tire.
Mix the concrete with water in a large bucket. Add water slowly and mix until the concrete is the consistency of thick pudding.
Carefully fill the tire with concrete using the spade. Make sure the whole tire fills with concrete and try to avoid air pockets. Fill the tire to the upper rim and level out the concrete. Use scrap wood to help hold the wooden "H" in place. Allow to set for 24 to 48 hours in a dry place.
Find the exact middle of the 8 foot by 7 inch board. Use a straight edge and pencil to mark a line on the underside of the board to identify the exact middle. Mark a second line 3/8 inch below the middle. Place a small "X" on the first line to avoid confusion later.
Screw one side of each of the four pipe saddle clips on to the board along the second line. Insert the pipe into the saddle clips and screw down the other side. The pipe should stick out by 3 inches on either side of the board.
Sit the 8 foot board on top of the wooden "H" so that the metal pipe slides between the 20 inch boards and rests on top of the exposed bolt middles.
To avoid bolt nuts from coming loose, place a dab of instant glue on the bolt threads behind the nut. Stain or paint the wooden portions of the see-saw as desired for a longer lifespan.
Always supervise children at play.