From a Positive Behavior Support point of view, mental flexibility can be achieved by first establishing a consistent routine/schedule then changing one (and only one) aspect of that schedule each day. Prior warning/review of any schedule changes should occur before the changes take place to give the person ample time to process the alteration and give them opportunities to find out more information. There should also be a clear explanation for the change so the person can see the benefit of doing so. While there may be initial resistance to the daily changes, if they are done consistently then the person will eventually come to expect to minor changes in routine and be more accepting when they occur.
Another way to achieve mental flexibility is to offer choices. Choices allow the person with ASD to see that there are multiple options available. Start with two options as too many options may be overwhelming. Be sure to make the options ones that can be carried out and would not cause distress for the person with ASD or the parent, caregiver, or educator. Choices can be simple such as what type of snack the person wants or more something complicated like choosing chore assignments. Choices can also be given when a preferred item or activity is not available, informing the person of what they can do or have instead.
For individuals with more language, once the person becomes comfortable with making choices, the next step would be for the person to generate their own options for choice. This can be achieved by asking the person to think of alternatives. This is typically a foreign activity for many people with ASD so it could be helpful to start this activity by using an area of interest or expertise. For example if the person's interest is sports, after watching a specific play during the game, you could ask them, what else could the player or coach done in that situation? If they suggest an alternative you could follow up by asking how that idea cold work better or what could go wrong with that plan. This ensures a logical thought process to the alternative. If the person cannot come up wit an alternative, options could be suggested and the person can discuss why or why not they would work. The important aspect of this is to help the realiz