Derailleur gears a detent or ratchet mechanism which stops the gear lever, and hence the cable and the derailleur, after moving a specific distance with each press or pull. Indexed shifters require re-calibration when cables stretch and parts get damaged or swapped. On racing bicycles, 10-gear rear cassettes appeared in 2000, and 11-gear cassettes appeared in 2009. Most current mountain bicycles have either. Many modern, high-end mountain bikes have begun using entirely one chain ring drivetrains, with the industry constantly pushing the number of rear cogs up and up, as shown by SRAM's Eagle groupsets (1 by 12) and Rotor's recent 1
Word sort will for most students lead to the abstraction of spelling patterns and the sounds to which they correspond. Word sorts can be teacher directed (closed) or student directed (open). For example, students in the with-in-word pattern phase of word knowledge could sort words according to a vowel pattern; in such sorts there is always a miscellaneous category for words that do not follow the target categories. Game-like formats such as board games and card games can also be effective if they focus on words that reflect spelling patterns. Word-building activities also facilitate abstraction of pattern: word wheels, flip charts, making