Stack n whack refers to the way the fabric is cut - you stack up your repeats (6 for a hexagon) and 'whack' out the shapes - here they are equilateral triangles. This term was coined (I think) by Bethany Reynolds who wrote 'Stacknwhackipedia'.
Kaleidoscope refers to the effect the block creates, this effect can be created by octogans, stars, strips, fans and any other number of shapes.
An OBW or One Block Wonder refers specifically to the technique developed by Maxine Rosenthal (books of the same name) where you layout your hexagon (or octogan) blocks so they all butt up against each other to create an allover effect - this is about the whole quilt rather than each individual block. With this technique, you sew the blocks in halves then pin them together while you do the layout. Then you join them in rows so NO dreaded Y seams!
Hope that's clearer than mud! :shock: :lol:
For more information on OBWs, stack n whack and kaleidoscopes, check out the Virtual Section by clicking on the link in blue at the bottom left of this page. :-D