Cognitive Tutor Authoring Tools 2.6 > CTAT Basics > Authoring ModesCTAT has three authoring modes for creating tutors. Since tutor development is inherently an iterative process, you will probably switch modes often while creating a tutor.
In Set Start State mode, you define the initial state for the tutor problem by interacting with the student interface.
Each problem has a single start state, which is stored as a section at the beginning of the BRD file.
You can set or modify the start state of the problem at any time during authoring.
To enter Set Start State mode, select Set Start State from the combo box at the top of the CTAT window. The tutor state will switch to its initial state, allowing you to enter or modify values that will be shown to the student.
![[Caution]](images/caution.gif) | Caution |
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Changing the start state for an existing graph does not ensure that new values you enter for the start state will be consistent with values throughout the rest of the graph. For example, if you change the given values in the fraction addition tutor, the other steps in the graph will still refer to the solution of the old problem (fraction addition with the old given values). If this is the case for your tutor, edit the rest of the tutor so that the values are consistent, or re-create the behavior graph (useful if it's a short problem with few steps). |