What We Liked: How it Works: Machines HD is SO neat! As soon as I brought it up on the iPad all of the children were clamoring around it for a turn. So I loaded it on our second iPad as well and we had little girls gleefully peeking inside of machines and making them work. The navigation of the app is really simple and straightforward, and the puzzle completion doesn’t require any previous technical knowledge about the placement of major parts, so it’s perfect for beginners. Even very small children can take a look inside these transparent machines and see simplified (but accurate) depictions of how these parts come together to make a working machine. The illustrations are all lovely and the app design is professional and well done. What We Didn’t Like: Nothing – this app is delightful! Overall: Peek inside nine common machines, put them together, then enjoy animations showing how they work! How Machines Work: Machines HD is a perfect app for tinkerers, curious children, and budding machinists – if you have a child who likes to take things apart and put them back together (or tries to), this app will be an absolute delight for them!