Most educators agree that well-planned lessons are a classroom essential. But some teachers don't know how to shape lessons. Others may not understand the subject they teach well enough to dream up creative ways of presenting it.
That's why, in recent years, more teachers have turned to the Internet to pool expertise and to sample lesson plans tried and tested by other teachers.
There are today about 10,000 websites that offer access to as many as 300,000 lesson plans. Many of these are free-to-all collaborative efforts that allow teachers to share their work with any who may be interested.
Others, however, are sophisticated for-profit businesses, offering packages that include extras like suggestions for related classroom activities, tests, and notes for Power Point slides.
The selection of lesson plans found on the Internet is remarkably broad. At lessonplanspage.com, 2,500 free lessons are available - including plans for gym, music, and computer classes.
At the discoveryschool.com site, users have only to select a grade and a subject matter to access lesson plans on everything from ancient history to the weather.
Edhelper.com offers logic puzzles and themed lessons treating topics like the national elections and the explorations of Lewis and Clark.
Some sites, however, are better than others - and too much information is sometimes as bad as none at all, say some teachers.
Combing through thousands of lessons is time-consuming, says Rob Lucas, who's starting his second year as a sixth-grade social studies teacher in Rocky Mount, N.C. He calls most of the online lessons "mediocre."
So to help teachers share their classroom expertise, Mr. Lucas, a Teach for America instructor, created a collaborative website called a "wiki" at teacherslounge.editme.com.
There is no charge for the service. Registered users can post lesson plans, links, handouts, and PowerPoint presentations.
No technical expertise is required. Wiki users also can modify other participants' posts. It's a high-tech version of the Japanese practice of continually improving lessons, known as "polishing the stone," says Lucas.
Charles Zaremba, however, took a different approach. Drawing on three decades of classroom experience, he refined his biology lessons, and drew more than a million visitors to his Mr. Biology site. Today, however, he sells his course through Teaching Point, based in Jacksonville, Fla.