That's exactly what I need to do. But first I need to go and scout it out to get it down to two devices, I don't want to overwhelm her.
You might even want to set her down in front of one of your computers and show her how the web and email works, just so she understands the concepts. That way when she's in the store, she'll have some reference base to use with the devices she sees there. The bigger screens and keyboards on the computers will make your little show-and-tell easier, but be careful you don't try to cover too much ground in one sitting.
With mom's boyfriend, I could tell he was interested in being able to look things up on the web, and in the quick communication of email (there was no instant messaging at the time), and he acted interested enough for me to purchase the computer for him. But even though he acted interested, or at least told me he was, he never touched it when I wasn't there. I don't know if he feigned interest so as not to hurt my feelings :confused2:, or he didn't want to appear stupid :shocked:, or was too polite to just say "no"

, but after several attempts to sit down with him and take baby steps, he still wouldn't/couldn't bring himself to dive in.
On my visits to Apple stores I've been met with very knowledgeable staffers that were eager to answer my questions and didn't mind repeating the answers if I wasn't keeping up (never thought I'd be saying this, but youngsters these days always seem to talk so fast it comes out as one long blablabla). Apple may even have free classes in the stores that are tailored to teaching computer skills to older folks; check their web site for details.
OTOH, I've been met with some outstanding BS peddlers at BestBuy, so take what you hear there with a large grain of salt.
Either way, if you take her to a store she'll see the prices on the devices, and that is both good and bad. On the one hand, she'll learn it's a significant purchase, and not to be taken lightly, but on the other she may not feel the capabilities are worth the price to her, an easy conclusion since she really doesn't understand what those capabilities are. If she grew up during the Depression, as my parents and mom's boyfriend did, she may also be very careful with her money, and be very hesitant to spend it on something she doesn't understand.
More :2cents: