2 boys, best friends, who live next door to one another, communicate with one another at or near bed time by writing messages on window shades and shining their flashlights up onto the shade. One of the boys may have been named Andrew. Early chapter book and it was a small series of books. The last one our teacher read to us, one of the boys was moving away at the end. This was read to my class in the 2nd grade (1989-1990), don’t know if it was newly published or something the teacher had been reading to her classes for some time.