Running App Inventor on a Tablet

While the usual setup is to build apps on a PC and then download them to a simulator or Android device for testing, it is also possible to use App Inventor in a browser running on a tablet, building and testing apps on the same device. However, the smaller screen and touch interface can make this challenging:

• On the Designer screen, instead of dragging a component onto the Viewer, 'long-click' to the right of the name of the component to select it (press until the highlight disappears), then click on the Viewer where it is to be positioned. Changing the order of the components on the Viewer works essentially the same way: click the component once to highlight it, then long-click to select it for moving, then click in its new position. Both of these operations are tricky to do initially, even when the display is zoomed in, but with some practice can be done reliably.
• On the Blocks screen, the code blocks are quite large relative to the screen size in landscape, but in portrait they're smaller and it's easier to get an overview of the program. To zoom in or out, pinch outside the Viewer area.
• To build the app, use the build APK for download option and the app will be downloaded and installed on the tablet directly.

In short, not a recommended approach, but workable if there are no other options.