The ideal way of building Apps using the MIT App Inventor platform is building your App on your computer, desktop or laptop, and testing it in real-time on your tablet or phone.
On your Android device, open the Play Store App and search for MIT AI2 Companion from the MIT Center for Mobile Learning. Click on Install.
Click on Create Apps! and sign in with your Google account.
Click on Start new project.
Name the project HelloWorld
Change the text to Hello World!
Properties -> Text
You'll notice the text on the screen updates to Hello World!
Click on Connect and select AI Companion.
A popup window appear with a QR code and a 6 letter code to connect your App to your device. On your device, you can either scan the QR or type in the code.
If all goes well, you’ll see Hello World! on your device’s screen! Any changes or updates to your program that you do on the MIT App Inventor website will appear on your device instantly.