What will you buy your nan for Christmas? What she probably wants is a pair of heated socks but you are a HuffPost UK Tech reader so it has to be something on the leading edge of technology. What could be better than an iPhone 8? OK, it's not an X but hey, it's the new product from a company, which is a leader in design, so it's got to be great at accessibility. It isn't. The way to switch on the accessibility features - such as inverted text so that a visually impaired person can see the screen is to find and open the settings app, find the 'General' section and tap on it, then find the 'Accessibility' setting and tap on it, then find and choose the 'Display Accommodation' option, choose the 'Invert Colors' (sic) and then decide if you want 'Smart Invert' or 'Classic Invert'. Sorry, I lost you at "find settings". There are two things broken here; discovery and implementation. The discoverability of the feature, it's up there with Douglas Adams' "beware of the leopard". It's not a feature you are going to stumble across, particularly if you are visually impaired. But let's assume someone has told you that it's in the 'Display Accommodation' setting and that the option has nothing to do with Airbnb. Think about the process by which a visually impaired person would get to the option. The first thing they would do is try and zoom on the screen. That's fine, even a moderately inexperienced iPhone user knows about pinching to zoom. Except it doesn't, while in an app the pinch works, but the home screen and settings are not an app - you need to switch on the zoom mode and double tap with three fingers to zoom. But getting to the zoom mode setting without zooming is impossible. On the lamented Windows Mobile phone, a double tap with two fingers zoomed regardless. The idea of UI problems where you can't complete an operation is called a UI trap and looked at on the website UItraps.com. Ultimately the iPhone, iPad and iOS are all horribly unfriendly for those with visual impairment. What you should buy your nan is an Amazon Echo Show. An Amazon Echo is a cool bit of tech and fits into the kind of thing that as a techie you should buy for someone, but it's not the tech appeal. Indeed many people mistakenly think that voice recognition is how to make a device suitable for older people. Saturday Night Live did a skit on a "Silver Alexa" where the Amazon device made sympathetic noises as an older man rambled on. What makes the Echo Show valuable is that it's a technology Trojan horse. Once your nan is up and running using the one killer feature of the Kindle Show there is a chance that she'll slowly, oh so slowly, be prepared to let you show you her how to do other things. It's not that older people can't use technology. Give an 80-year-old engineer a slide rule and he or she will be a damn sight more comfortable with it than you or me, it's all about familiarity and nothing about any new piece of technology is familiar. You might think that it's obvious that an arrow pointing right means "play" or a circle with a line in the middle is an on switch, but it's all still alien. The Kindle Show doesn't solve that problem. What it does give your nan is a compelling reason to learn. The one killer feature is you. Research from the Department of Engineering at Cambridge University has found that an older person will take on something which is a significant cognitive challenge if the reward is great enough, and for your grandmother, there is no greater reward than video calling grandchildren. Don't call it Skype or FaceTime, it's just you on the seven-inch screen in her kitchen. Teaching your gran to video call isn't the best technology for her, services like Fuss Free Phones take an alternative view of shaping technology to suit older people's existing mental models. Whatever you do, don't buy her an iPhone 8. And the great advantage of getting your nan an Amazon Echo Show is that you'll have to get one too.