There is always lots of discussion regarding ways a differentiated spelling program can be implemented. Here are some discussions to spark ideas:
http://www.surfinthroughsecond.com/2013/01/differentiated-spelling.html?m=1
http://emilykissner.blogspot.com/2010/07/differentiated-spelling-in-classroom.html?m=1
Here is the correct link for the spelling lists referenced in the above link -
http://www.teacherspayteachers.com/Product/Differentiated-Spelling-Program
http://www.surfinthroughsecond.com/2013/01/differentiated-spelling.html?m=1
http://emilykissner.blogspot.com/2010/07/differentiated-spelling-in-classroom.html?m=1
Here is the correct link for the spelling lists referenced in the above link -
http://www.teacherspayteachers.com/Product/Differentiated-Spelling-Program