A Goose Whistle
Cut out the three strips of paper. take one of the papers an fold in half on the middle line (so that the colors are on the outside) . Cut out the triangle in the middle to make a little notch.
Fold the ends (on the dotted line) away from each other.
Hold the whistle up to your mouth (at the open end) and blow gently.
Splash tip: It helps to keep the end open just a bit.