People use both abstract and concrete language everyday. Some people think and speak more in either the abstract or concrete but they can understand both. A person with FASD may speak to some degree in the abstract but they think and interpret concrete concepts.
This fact, that people with FASD, work in concrete terms affects the way that they have to be taught. In the school, teachers will find that visual aids will help in learning. Also, communication will be clearer through visual aids. This is sensible and helps remind anyone working with the student to use this direct approach.
Its interesting that people with FASD would use abstract words in their speaking since they are unlikely to understand those words. This is a result of language acquisition and not suggestive of learning abstract thought. This concept is one of most important facts about working with people with FASD. If a worker/family member/teacher understands this fact then it can ease a lot of frustration for both parties as they learn to "show and tell" in the concrete.