Many people with ADHD have trouble with working memory.
Our working memory is where we store information temporarily "in the moment". We use it for planning and problem solving. It's our ability to remember information long enough to do what are doing.
When our instructor gives us an assignment we will hopefully remember it long enough to get it written down in our notes so that we can use planning brain later on to create needed steps to complete the assignment.
When working memory isn't working properly we don't hold the information long enough to complete the task.
For example, maybe we get distracted before we write down our assignment and then don't remember what the assignment is when it comes time to get it done.
When we improve working memory we improve our ability to problem solve and adapt in the moment. It is important to be able to rely on ourselves to keep relevant information available in our brains while we problem solve.
There are lots of strategies for improving our capacity for using working memory.