My personal experience with block scheduling has convinced me that the "block" is achievement neutral; that is, block scheduling doesen't affect achievement either positively or negatively. In fact, it seems that factors involved with the block cancel each other out.
Block scheduling can become very polarizing as different faculty members and departments fight for favorable schedules within the block.
Block sheduling does wonders for school discipline and overall climate. Since you only have three to four class changes, the kids only mix with (and set off) each other three or four times a day. Your building will be much quieter! This has very positive effects on teaching.
But, this is balanced by the fact that you don't see your kids every day (within the A-B mode of block). This has negative effects on teaching.
The straight 4-period block does not have the infrequent pupil contact problem of the A-B block. Its primary problem is district-to-district articulation when children from other districts which are on standard schedules enroll or when you send your children to any districts that are not on a straight block.
People who have not implemented Block scheduling successfully have tended not to use change theory effectively and have not provided adequate training.
Also, the most effective Block models try to be flexible.
Block Scheduling Links
Other Block Schedule Links.
Negative Stuff about Block.
Still more Block Stuff
Block Scheduling FAQ's
Implementation report
