If your helper is forgetful try giving her a 15 minute nap after lunch? Does her performance slowly degrade during the day? A 15 minute nap may be the key to rebooting her brain and upping her performance.
Here is a link to a fascinating article on napping and the brain. It is backed by copious research, but written in a style that even I can understand. If your helper is absent-minded, forgetful or seems to be underperforming, why not give her a nap? What do you have to lose? We're talking about 15 min.s to 1/2 hour max. Here's the link: