New App Inventor Curriculum for SF Middle Schools

screen-shot-2016-09-14-at-10-14-52-amThe San Francisco Unified School District (SFUSD) is making great strides in rapidly adding computer science courses to the curriculum in public middle schools and high schools, and App Inventor is a vital part of it.  SFUSD’s Bryan Twarek and Andrew Rothman have designed an on-line middle school curriculum which combines video and other lessons from,,, and a number of other venues, and breaks lessons down into 50 minute classroom chunks. The well-organized site is being used this fall in SF middle schools. Check it out and contact Bryan ( to get access to the teacher side of it.

The middle school curriculum is part of SFUSD’s Computer Science for All Students in SF effort. The goal is to make real computer science– with coding and problem solving– part of the curriculum throughout the grade levels, and to help broaden participation in Tech, as this excerpt from their site attests:

By beginning in the earliest grades and with all children, we will normalize a discipline that has been long dominated by a selective group of the population.

SFUSD teachers are also teaching some of the first AP High School Computer Science Principles (CSP) courses on the West Coast, an effort led by SFUSD’s Jennie Lyons.

The Democratize Computing Lab at the University of San Francisco is  partnering with the school district in these efforts. Led by my colleague Alark Joshi and I, we provide materials and advice on curriculum development, offer summer training workshops for high school  teachers, and facilitate a program whereby USF students in the Democratize Computing Lab assist teachers at schools sites each semester.

Dave Wolber

Test Your App Inventor Knowledge


If you have been reading App Inventor tutorials, discovering new apps in the App Inventor Gallery, building apps from scratch and expanding your coding capabilities, its time to:

Test Your App Inventor Knowledge!

This simple quiz will determine if you’re on track learning the latest updates to the App Inventor platform.

Question 1

You are frustrated because of the limited color options available in the App Inventor Designer, so you use:

  • A)   the color grid in the Blocks Editor
  • B)   the Make Color block in the Blocks Editor
  • C)  the Screen Initialize and Set Background Color blocks

Question 2

You have a lot of data to display and want to create a streamlined UI, so you use which of the following Components?

  • A)   VerticalArrangement
  • B)   TableArrangement
  • C)   VerticalScrollArrangement

Question 3

You want to change the shape of some Buttons, so you use which of the following properties?

  • A)   Width
  • B)   Shape
  • C)   Image

Question 4

When creating an app with multiple screens, you can use which of the following blocks?

  • A)   Close screen
  • B)   Open another screen
  • C)   When Button1.Click

Question 5

To create a form in the Designer, which of the following could you use?

  • A)   Textbox Hint Property
  • B)   Label Component
  • C)   HorizontalArrangement Component

Question 6

To create a new color in App Inventor with the Make Color block, you could:

  • A)   Input any color’s RGB value
  • B)   Access one of 16 million colors
  • C)   Find a color on the Adobe Kuler Wheel

Question 7

To make a copy of the app you are working on you could use:

  • A)  Save project as
  • B)  Checkpoint
  • C)  Export selected proejct

All About Buttons

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Buttons are an essential component in creating mobile apps on App Inventor. You can use them to do things like submit information, navigate screens, clear data, and stop or start game play. Here is a quick intro guide to creating and using buttons in App Inventor.

The Button component is found at the top of the User Interface Palette in the Designer.

Click on the Button at the top of the User Interface Palette (#1) on the left side of the screen and drag it to the Viewer (#2). The Button automatically displays “Text for Button1”, which you can easily change in the properties panel text box (near the bottom on the far right of the screen, #3).

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Changing the text that appears on the button is part of the UI design that the app user will see. Depending on what the button will be used for, it could display instructions like: “Submit,” “Next,” “Play,” etc.

Note: Changing the button display text should not be confused with renaming the button. Changing the button name helps you, the designer/coder, to keep your buttons organized. Thus “SubmitButton” is an appropriate name for a button that displays the text “Submit”.

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A key coding principle for buttons (and for many components) is naming them appropriately. Whenever you create a new button in the Designer, it will automatically be named Button1, Button2, Button3, etc. When you first start building apps, your interface will be simple and thus it will be easy to keep track of which buttons perform which functions. But as you progress to creating more complex applications, you will quickly discover that it is difficult to remember what Button7 or Button14 does. Thus, it is good practice to rename buttons to clearly describe their function so that when you begin coding in the Blocks Editor, each button purpose is obvious.

The recommended standard is to use a capitalized descriptive name, followed by the capitalized component name – with no spaces between words. Examples include: “SubmitButton”, “NextButton” or “PlayButton”. (AppInventor doesn’t allow spaces so if you type the name “Submit Button” with a space in between the words, App Inventor will automatically insert an underscore and name your button “Submit_Button”.)Screen Shot 2016-06-21 at 9.58.14 PM

To rename a button, activate it by clicking on it in the Viewer or in the Components Panel (it will highlight with a light green box around the name). Then click the “Rename” button at the bottom of the Components Panel (#4). A pop-up window will appear, insert the new name into the text box and click “OK” (#5).

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Note: If for example you rename your first button from Button1 to “PlayButton”, and then drag another button onto the Viewer, App Inventor will name it Button1 even though it is not the first button you created. ThScreen Shot 2016-06-21 at 10.10.21 PM.pngis example illustrates the importance of not relying on the order of creation, but rather on appropriate naming to keep buttons organized.

Any changes you make in the Designer will be reflected in the Blocks Editor (#6). Notice at the bottom of the Blocks Palette, there is another option to Rename (or delete) buttons. Thus, changes can be made there as well.

Screen Shot 2016-06-21 at 10.22.24 PM

If you decide that a button is no longer needed, deleting it is simple. Click on the button in the Viewer or Components Panel in the Designer or in the Blocks Panel in the Editor and then click “Delete”. A pop-up window will confirm deletion (#7). Click “OK”.

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The Properties Panel in the Designer provides many options to change the format of your buttons. Click on the button in the Viewer or the Components Panel to see a list of options. The changes you make to the properties are reflected in the Viewer (#8 & #9).

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And of course, to get the full effect of how your app will look, it is always recommended to view your changes live on your mobile device or with the on-screen emulator.

For information on coding buttons, stay tuned for All About Buttons, Part 2.


What the Heck is Checkpoint?

At some point, all of us computer users have experienced the pain, frustration and anxiety of losing some amount of work due to an application that has “unexpectedly quit”. Losing your work to a system error needs to only happen once before one becomes more vigilant about saving work or creating a backup. When creating apps in App Inventor, it is easy to forget to “save” because the platform does it for you (every 5-30 seconds). In theory, there is no need to save a project that is already being saved. But, in reality, I would recommend to save, save, save.

Given that advice, what are the App Inventor saving options?

You can save projects in App inventor and to your computer. All of the options are under the Projects Menu (in both the Designer and Blocks Editor). You will find Save project, Save project as… and Checkpoint along with Export selected project (.aia) to my computer and Export all projects.

Checkpoint 1Save project is the manual version of the automatic save feature. It merely reassures you that your project is saved and you continue working in the same version of your project. Use Save project for peace of mind.

Save project as… works similarly to a Save As in Microsoft Word. It allows you to save the project with a different name and afterwards, begin working in the new version of the project. Your previous version is saved in My Projects. Use Save project as… for peace of mind.

Checkpoint also makes a copy of your current project, but allows you to keep working in the original project. Creating a Checkpoint, essentially takes a snapshot of your project at a point in its development and saves it in My Projects. You may want to create many Checkpoints along the course of building your app as it grows in complexity. For example, if you create a Checkpoint before you add a database then encounter a problem or a bug that you are not sure how to fix, you can always re-open the Checkpoint that did not contain the database and start anew.

When you create a new Checkpoint, App Inventor shows you a list of previous Checkpoints and the time/date they were saved. Checkpoint 2

Once you have completed your app, you always have the option to delete or keep your Checkpoints. Use Checkpoint for peace of mind.
Checkpoint 3

In addition to saving your projects within the App Inventor platform, you can also export your projects.

Export selected project (.aia) to my computer is a feature I cannot recommend enough. It’s easy, easy, easy to save an .aia file to a location on your computer and/or to an online storage system like Google Docs or Dropbox. And if you ever need to open that .aia file, just select Import project (.aia) from my computer… to bring it into your projects list in App Inventor. Use Export selected project (.aia) to my computer for peace of mind.

Tip of the day: For complete peace of mind, save your work within App Inventor and export your work to your computer.



FirebaseDB is the new App Inventor web database. Kind of. The uncertainty stems from the fact that this new web database component is currently being beta tested and will be updated based on user feedback. You can try it out, but don’t get too attached to its current form, because features may change by the time it is fully integrated. In case you forget this fact, you will be reminded every time you try to add this component to your project. Housed under the “Experimental” Palette drawer in the Designer, dragging this non-visible component to the Viewer will result in an alert reminding you of its provisional existence.

Fire 1Fire 2

I already love FirebaseDB and use it as if its current form were a permanent addition to my coding repertoire. Why is FirebaseDB so great?

Databases are used for many of reasons in mobile apps such as: to keep track of high scores in a game, to count the number of votes in an election, to save a variety outgoing text messages or to store the names of RSVPs to a book club event. FirebaseDB stores data in the cloud, which is helpful if you are perhaps vying to become a high scorer of a game. For such apps, both the app programmer and app user want this sort of data to be shared and persistent, meaning that once the app closes, the information is not gone forever, it will be saved and retrieved for all to see once the app reopens.

Fire 3.png

Example: For a simple note-taking app, users enter their username and a note and the app will display the note, the username and a time/date stamp. For this app to work, it must save and display notes from different users on various devices- a perfect scenario for FirebaseDB.

We programed this app so that when the user clicks “Submit,” the app stores data using the StoreValue block. In this case, it adds the values (user’s name, note, and date/time stamp) to a list called “global notes”. This information gets stored in the FirebaseDB under the tag that we named, “notelist”.

Fire 4.png

Each time the app opens, the GetValue block requests the most updated values stored under the “notelist” tag from the Firebase Service. When the value is received, the GotValue event fires retrieving the values saved in “notelist” and displays them in a List View.

The Firebase DataChanged event gets triggered anytime any user adds a new note. This is the amazing part because with FirebaseDB, all app instances receive this data and thus, are consistent. The previous App Inventor web database, TinyWebDB, did not have the ability to share data globally in this manner.

Fire 5.png

To become familiar with FirebaseDB, try building this note taker app and test how values from various users get saved, updated and displayed Or better yet, build a game app and see people around the world vie for the top scorer position!




*Note that the App Inventor emulator does not support the FirebaseDB component.



Hue New?

One only has to read a few tweets about the Uber or Instagram icon re-design to know how passionate people feel about mobile app design. Creating a Color blog 1user-friendly (and pleasing) interface is as important as creating code that functions properly. Many App Inventor users assume that all UI features are found in the Designer. However, this is not the case in terms of colors. Over and over, I hear people reveal their frustration about the limited amount of colors available in App Inventor. At first glance, the Designer does seem to only offer a list of 8 saturated colors, along with white, black and a few grays. But really there are a multitude of color options if you know where to look. All you need to do is head over to the Blocks Editor.

Notice in the left menu, under “Built-in” there is an item called: Colors. Clicking on it reveals a list of color blocks that would once again lead you to believe that saturated colors are indeed the only options. Don’t be fooled.Color blog 2.png

Once you click on a color block, it will appear in the Viewer and clicking again on the actual color inside the block reveals a 7 x 10 grid of color hues! Hue new? Now you can select pastels, deeps and a range in between.

Color blog 3.png
What can you do with all of these color options? Well, since they are housed in the Blocks Editor, you can incorporate them into your code. For example, you can change the color of a component, (a button, a label, a screen background, a layout) by using the screen initialize block.

Color blog 4When your app launches or when you make a change in the Designer, the components will receive their newly hued instructions and your previously boring grey buttons will come to life!

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App Inventor Education Taking off in China!

There are many stories about competition and strife in US-China relations, as well as the profound differences in our cultures. This is a story, instead, of collaboration, the story of US and Chinese citizens uniting for the common goal of better educating students for the 21st century. What better agent than education to illustrate the amazing commonalities between peoples?

MIT App Inventor is the catalyst of change, a coding language perfectly suited for teaching and inspiring young people to learn how to create and solve problems in our rapidly digitizing world. While App Inventor education has rapidly expanded in the US since its inception at Google in 2009, it has been widely unavailable in China. Thanks to the efforts of the extended MIT App Inventor team and some extraordinary educators in China, this creative way of teaching computational thinking is now also taking off in China.

Hal Abelson, director of the MIT App Inventor team, has led the project from the US side. App Inventor was inaccessible in China because it runs on Google infrastructure, so Hal, Jeff Schiller, Weihua Li, Andrew McKinney, and others facilitated the creation of a version that runs on a different infrastructure and thus can be accessed in China.

But this was only the start. With the help of the extraordinary MIT student Weihua Li, a plan was set in place to jumpstart App Inventor education in China through teacher and student workshops starting in the summer of 2014. The idea spread like rapid-fire and led to the 1st International Conference on Mobile Learning and Computational Thinking Education, Based on App Inventor, which was held in Guangzhou in June (2015)..


Attendees of the App Inventor Conference in Guangzhou. See if you can pick me (David Wolber) out. Hint: I’m the tallest.


Li Yue, South China Univ. of Technology


The conference included representatives from Hong Kong, Taiwan, UK, UNESCO, and the US, as well as over 200 educators from all over China.

I was honored to speak at the conference and to teach a workshop to some K-12 and university teachers. Ralph Morelli of Trinity College and also spoke and gave a workshop to about sixty middle schoolers, shown below. MIT was represented by Tech Lead Andrew McKinney, Felicia Kamriani, and the aforementioned WeiHua Li, who spoke at the conference and was also the key translator for the English speakers.

The real story, however, is the amazing efforts of educators in China who are helping spread App Inventor based education throughout the region and country. It is a joint university and governmental project perhaps best exemplified by South China University Professor Li Yue, the conference organizer who has led numerous teacher training workshops throughout South China. I was honored to see her in action, using her relentless energy and charm to teach and inspire.


The students at Ralph Morelli’s workshop were extremely diligent as Ralph walked them through building a “Selfie-Slideshow app”

Dr. Li organized a visit to a school where we saw first hand how App Inventor is making a difference: a roomful of energetic middle school students energized about building apps. Ralph Morelli gave them a workshop, teaching them how to build a “Selfie-Slideshow” app, and it was incredible to see the joy on the student’s faces. On a personal basis, I was happy to see that the students were using a translated version of the App Inventor book I co-authored (along with Hal, Ellen Spertus, and Liz Looney).

Screen Shot 2015-07-03 at 2.43.38 PM has a translated version of the book App Inventor: Create your own Android Apps

The conference and workshops didn’t solve the world’s problems, but a group of educators from East and West shared ideas on how best to educate young people for the jobs of tomorrow (as well as ideas on one-child policies, free speech, gun control, and the best Beatles songs to play at Karaouke). It was a highlight of my career to participate, not only to help spread a great method of educating students, but to help promote a collaborative spirit between the peoples of China and the US.