Note: I use the 'Bootcamp' curriculum for kindergarten, which starts all students off at the exact same place in the first week of school: alphabet bootcamp. Students all learn starting from 0 and progress as a group through alphabet, sounds, vowels, vowel teams, Blends, CVC words, etc so the differences are very small in my experience with my preschoolers and my observed experiences of other teachers using this curriculum. Most students are at least on target with some gifted and talented students who are ahead. Most of my observations and personal experiences with this curriculum there was often 0 students not meeting learning targets, and if there was a student or two not meeting targets, it was easy to support them in a differentiated small group setting.