Next, set the protractor device outside in an area that receives unobstructed sunlight all day. Lay a carpenter's level lengthwise, and then widthwise, to level the board. Pile a little sand or small stones under the board to level it.
The reference point of zero on the protractor will be held constant (the plywood and protractor will be kept level horizontally with the ground). The movement of the Earth is the variable in this project.
About two hours before midday, begin measuring the angle of the Sun's altitude by placing the point of a pencil by the base at the middle of the protractor, and raising the pencil up or down until no shadow of the pencil is cast. Remember, do not look directly at the sun during this project. Check the angle of the pencil by reading the increments on the protractor.
Make these measurements at ten-minute intervals. Write down the angle of the Sun's height.
Continue making measurements until one hour after the Sun's angle begins to decrease.
Did the Sun's peak height occur at about the time you calculated the midpoint between sunrise and sunset?