Producing graphic images on a PC can sometimes feel like a hurdle. Sure Microsoft have introduced SmartArt whose predefined formats can be a blessing when they correspond to what you need but are a barrier the rest of the time.
Can I introduce you to Grafio, my favourite app for diagramming on the iPad - not forgetting of course that anything you draw on your iPad can be used on your computer in documents you are working on there. Grafio makes creating amazing looking diagrams both easy and fun - I love it! It's not just me either, I know one deputy head who loves Grafio so much that she uses it capture ideas during meetings and shares the resulting work as people leave the room.
There is no substitute for trying something out for yourself so, with nothing to lose, I would encourage you to download Grafio lite, use the getting starting guide and give it a go. If you like it, you might always be tempted by full Grafio (£5.99 non education/vpp pricing). Sadly we've just missed the Thanksgiving price reduction that they had last week but this app is so useful it is definitely worth the money. Davinia has been using this with some of her students and it has been a big hit.
Have a look at the Grafio website for more information!
If you watch this YouTube video whilst following along on your iPad you will grasp the basics in less that five minutes.