I used both AppInventor and Thunkable. Both of them have very unique features, pros and cons.
AppInventor is more stable and there are so much information and tutorials online you can take it as references; Thunkable supports both Android and IOS and it could run/test most of finished apps on their website (new live function).
Of course you can choose one according to your needs, I teach both of those platforms with students. But for a large group (30-ish students), I would choose Thunkable.
Here are several reasons why I use Thunkable:
We run IOS on all our devices, Thunkable is so much easier for app testing (live test on the site or ThunkableLive apps on iPad and iPhone).
The layout is delightful, students love to work on it.
For the large size classes, I focus more on "finishing" the assignment. So Thunkable can perform with easy projects, which is the goal I want. For more capable students, they can extend the project as they want (we always have choices in lessons).
I realize that during this special lockdown time, App Design can be a brilliant topic to teach - students can have more time to work by themselves with the provided platform. Also it is not limited by the form of lessons, as long as everyone can access to the internet.
Besides, easy to coach - all you need to do is to share each other's screen, you can always find bugs and de-bug them. Isn't it the wonderful way to learn and teach remotely?
There are four projects included in this unit.
The first one is Random Name Generator. It is easy to create as an introductory project in the very beginning for students who are new to Thunkable and App Design. It doesn't take much efforts on neither designing and coding.
Here is the link of the instructions (It's pretty easy so I used text-based instructions):
The second app is called The Doodle App. Students can create an app with doodling function. They can draw on it. Students can add multiple pictures and choose the one that they want to draw (extension for capable students).
Starting from this project, I use video tutorials to guide students as it can be easier for them to follow.
Here is the playlist of this app: https://www.youtube.com/playlist?list=PLMmtuxBnhMfxE8KGepH7c9Jk_g4VzQlgu
The third one is called Bunny Mash. It makes a sprite (mine is bunny in the example) to move randomly in a specific area and to catch it by tapping on. Players will get a score on it. It is a very easy game app and students can customize it according to their own taste.
I divided the tutorials into four parts - demo, design, code and test. (with sequences)
Here is the playlist of this game: https://www.youtube.com/playlist?list=PLMmtuxBnhMfxsmWdUnXcwIwnZiZ346cgv
The last app is a translator app. Since Thunkable has the function of translator, making a translator app becomes so easy. So I give students the idea about it and guide them to create their own translators. It is a bit complicated comparing to rest of projects in this unit. But still, it's really easy to understand. I added explanations in tutorials.
The sequence of the playlist should be design part, code part and test.
Here is the playlist of it: https://www.youtube.com/playlist?list=PLMmtuxBnhMfz4Um0W-IShYvqTIwHPa7nD
Target Students
You can use it with upper primary or introductory unit of app design with middle schoolers. I used it with Grade six students. Most of them worked really well considering the distant learning situation.
I do like it and think I will make more projects about Thunkable for lesson use in the future.