I feel all of us need some amount of reference to maintain our memories of things in our lives.  I feel special education students especially those who suffer cognitive problems will continually have problems maintaining those memories unless those tasks are well bridged by other knowledge to help maintain those memories.  When I taught MID and MOD students, this was a never ending problem for me.  If you achieve some long-term memory in those students, good for you, but it is a continual work to maintain it.