When a middle school student is able to demonstrate that he/she is able to hear a string of digits (1, 2, 3, 4, etc.) and then repeat the string in reverse order several seconds later, the child is indicating that he/she is developing?

I believe the answer is: Working memory

Working memory plays part in the brain activities that we done consciously and usually stored only for a short period of time. . This would include in activities such as recollecting the information that is just given to you or visualizing the clothing of the person that just walked pass by you.

Apart of the parietal lobe

It allowed for things to be produced much more quickly and efficiently