The article "Christmas Tree Lights -- A 'Continuing Series'?" which
appeared in the December, 1992, issue of The Physics Teacher
(volume 30/Number 9, pages 530-532) is now online on the Physical
Sciences Resource Center(http://www.aapt.org/psrc) under the "How
Things Work" icon. This might be a particularly good topic for the last
week of school before Christmas.