"How long is a second?" "A second is a hiccup--the time it takes to kiss your mom, or jump a rope, or turn around." The newest book by acclaimed picture-book creators Hazel Hutchins and Kady McDonald Denton explains units of time in imaginative terms children can understand: A second lasts as long as a hiccup; a week is seven sleeps; and a year is the time it takes to grown into new shoes! A…