A hygrometer is an instrument that measures the humidity in the air.
You can make a homemade one with cardstock, a brad and a strand of hair.
Punch a hole in a half-sheet of cardstock about halfway down the side. Cut a thin strip from the other half of the cardstock, and cut a point on one end of it. Punch a hole in the other end of it. With a brad, attached the end with the hole to the hole in the other piece of cardstock.
Tape one end of the strand of hair to the pointed end of the strip of cardstock. Tape the other end of the hair to the back of the card, letting the hair go up and over the top of the cardstock. The pointed strip should hang in the middle of the card as above.
Mark the card where the pointed end of the strip hangs with the date. Place the hygrometer outside in a protected place. We taped ours to a box which is open at the top. Mark the position of the strip to see how it rises and falls with the changes in humidity.Pin It