Embodiments can provide a computer implemented method in a data processing system comprising a processor and a memory comprising instructions which are executed by the processor to cause the processor to implement a reading skill assessment system, the method comprising creating one or more sets of parameterized text mutators for one or more different reading skill levels; applying a reading skill score function to calculate baseline scores for one or more tested reading skill levels; adjusting the reading skill score function to best match with the one or more tested reading skill levels; optimizing the parameters of the one or more sets of text mutators; creating one or more baseline reading skill score levels for each of the one or more tested reading skill levels; and associating one or more sets of text mutators with the one or more tested reading skill levels.