Notes for Collins, 1992,Toward a design science of Education
Reading this article makes me beginning of thinking and knowing what is a design theory.
There is an interpretion for this conception at page 19:
"...This design theory will attempt to sepcify all the vairables what values on these variables maximize chances for success, and how different variables interact in creating successful designs"

After reading this article, I searched the meaning of some points I don't understand.
There are definitions and my understandings of these points:

• Satuation(p.20). At first I guess "saturation" is another terminology from quantitative or other field . Then I searched on google and compared the meaning of "moderate saturation" and "high saturation" according to the context . Then I decided here saturation is only the ratio of computer / student. When the computer / students  is high, like every student can use one computer, that is a high saturation, and students could work for learge amounts of time on projects with the teacher acting as a coach, according to this article.Contrarily, when there are several students using one computer, that is a moderate saturation, and activity centers in the classroom may be the basic teaching type.
• What is "Subject-matter learning"? As my understanding, subject-matter learning is learning focus on a specific subject. The goal is to impove students' learning of this subject.
• "Susan Loucks"' seven levels of expertize teachers move through as they gain greater ease and sophistication.??????????
• What is "Activity-centered classroom"?
  
• Stevens describes it as an enviroment where:
•            Students choose their own areas of study within the theme suggested by the teacher.

•            Students do whatever is necessary to find the information required to pursue their projects.

•            Students present their findings in some form that they have selected, such as a  model, a picture, a written handout, or whatever means they consider appropriate.

•            Students use each other as well as the teacher as resource persons.

• By Cindy LaVan
  Activity-centered classrooms allow students to participate in hands-on activities. The goal is to improve aural comprehension and oral fluency, but students can also be involved in reading and writing activities. A theme is suggested by the teacher, and students chooose their own area of study. They investigate the topic, then present their findings in the form they choose.
  
  
• What is "Tom Snyder's Search Series"?