One aspect of the andragogical model that disturbs many people is that not all adults seem to fit the assumptions. Any facilitator of adult learning will tell you that adult learners are not as homogenous as the andragogical model implies. Research has shown that there are many individual differences among learners that interact with the core adult learning principles to shape adults’ learning behaviors. As noted earlier, the andragogical principles are powerful but incomplete descriptors of adults’ learning behavior. Experienced adult learning professionals have learned that, like most models, the andragogical learning principles are tempered by an array of other factors that affect learning behavior. Knowles (1984b) reinforced this when examining lessons learned from andragogy in practice: “The andragogical model is a system of elements that can be adopted or adapted in whole or in part. It is not an ideology that must be applied totally and without modification. In fact, an essential feature of andragogy is flexibility” (p. 418).