Color

Use a limited set of bright, bold colors. These colors should act as guides, identifying specific content and interactions. It’s tempting to splash color all over the screen, especially for kids with short attention spans who can’t read, but too many colors in them can cause these little guys to get overwhelmed, so they lose interest quickly.

Navigation

Keep your navigation simple. If you make navigation elements wiggle and make noise, kids won’t realize they have another purpose other than to wiggle and make noise. It’s natural to want to draw attention to navigation items by adding sounds and actions, but if you do so, your users won’t understand they can touch them to watch different videos. You can use size and color intensity to highlight the video currently playing, but keep animation and sound to a minimum.

Icons

The 2–4-year-olds are not able to think abstractly, so avoid using icons and symbols, even ones that may seem completely intuitive. You can, however, start introducing some basic shapes that mimic items kids are familiar with in the physical world, such as arrows, stars, and “thumbs-up” signs. Using forward- and backward-pointing arrows to indicate the presence of additional video content will resonate with users at the older age of this range, say, 3½- to 4-year-olds, but will likely be ignored by the littlest kids.

Video

For the record, as a user, I hate auto-play; however, when you are designing for kids under 4, auto-play is your friend. Make the steps between accessing the app and actually playing a video as few as possible, so kids can quickly understand the purpose of the app and start using it successfully. Also, make auto-play an option that parents can turn on and off in a parental controls area, but default to auto-play on install so kids can get the immediate gratification they’re looking for.

Scrubber

Because kids this young don’t really understand icons, all you need is a basic play/pause button and a scrolling timeline in case parents need to rewind or forward to specific parts. It’s also nice to throw in a counter so parents can see how long certain videos are and how much is left to watch. Since kids get bored easily and usually don’t watch videos to the end, you can hold off on adding full-screen functionality until your audience gets a little older. But kids should be able to switch quickly between videos instead of focusing on an immersive entertainment experience.

On-Screen Elements

While littler kids require larger targets and broader gestures, older kids’ motor skills are better developed, and they can interact more easily with finer on-screen elements and smaller gestures. You can shrink navigational elements for these guys so you have more room for a larger content area and more detailed functionality.

Saving and Storing

The idea of permanence starts becoming important at this age. Give kids the opportunity to save their favorite videos so they can easily access them whenever they want. This functionality doesn’t have to be complicated, but it should be personalized (first name is fine) and accessible from everywhere within the app.

Sequence

When kids are around age 4, narrative and flow become a bit more important to them, as they start understanding more complex scenarios. Younger children like abstract exploration, but these folks like sequential discovery. As a result, you may want to let kids seamlessly switch to the previous and next videos in the line-up without requiring them to remove themselves from the experience and go back up to the app navigation.

Auto-Play

You can turn off auto-play now. Kids from 4–6 like to have a little more control over their on-screen interactions, so allow them to choose when to play the video. A very simple “play” button in the middle of the video screen is all you need, as long as you have your standard play/pause functionality in the scrubber.

Favorites

When kids are this age, it will be important to give them the ability to save and store their favorite videos. A simple favorite selector, in the form of a heart or a plus sign, lets kids add items to their favorites menu. (I actually think the heart works better here, since kids understand that hearts mean love.)

Navigation

You can introduce the standard mobile navigation bar at this age. While these kids are still wrestling with abstraction, they understand basic iconography and have most likely learned what the major mobile icons represent. Keep the functionality in this navigation bar as simple as you can, with as few options as possible, just to get kids familiar with this type of interaction. You can also use gestures as navigation here.

Instructions

Give these kids as much up-front instruction as they’ll need to get started using the app. With these kids, as with adult audiences, you’ll want to avoid superfluous content, but a basic overview of the app’s goals, benefits, and first steps will be super-helpful for these guys. When they get a little older, they’ll skip right over the instructions, but at this age, they’ll read every word if it will make it less likely for them to make a mistake.

Labeling

For 6–8s, you’ll want to err on the side of overlabeling rather than underlabeling, simply because these kids want to know exactly what everything on the screen is or does, and how it should be used.

Consistency

Similar to designing for adults, when you design for these kids, you should carry over color/icon treatment whenever you reference a specific category, so the users have a sense of place and context. Try to avoid deep nesting of content, because these kids will get stuck and have a hard time figuring out where they are in the app. When they get a little older, you’ll be able to introduce the concepts of nesting and cross-categorization.

Lists and Inventories

It’s a good idea to let these kids see what other items (in this case, videos) live in the category they’ve selected. For littler ones, having a single item per category, or elevating individual items to the topmost level, works well, since they aren’t great at classifying objects or information, but older kids like organization and structure, and can understand how objects are grouped. In this example, you can see all physics videos listed to the right of the player, so kids can easily jump from video to video in case they feel as though they picked the “wrong” one to watch.

Scrubber

You can add additional functionality to the scrubber, such as “add to playlist” and “expand screen.” Kids are familiar with these concepts and will be able to successfully interpret and understand the standard icons.

Ratings

While these guys are a little young for traditional ratings and reviews (they get confused about where the ratings come from and why they should care), it’s a good idea to let them share their opinion of a content item and to store it in the app. Here, the traditional “thumbs-up” and “thumbs-down” symbols let the kids rate the videos, so the next time the video appears in a list or in search results, they’ll be able to recall how they felt about it.

Descriptions

These children like context, so you’ll want to provide a brief description of each video. (If you can also supply voice-over audio for the descriptions, all the better.) If kids understand what they can expect to see in the videos, they’ll feel more confident about choosing the “right” one to watch.

Search

Kids on the younger end of this age range probably won’t use search functionality a whole lot, but older kids will, especially if there are videos they want to access right away. You can use simply a field and the search icon here, as these kids will know just what to do.

Dynamic Classification

Our 8–10s are incredibly curious about the world around them. Instead of reading instructions, they want to just jump right in and learn as they go. What seems to be compelling for these guys is to get a glimpse into what other users are doing within the interface. For example, with a video app, you might create dynamic categories such as “Most Watched” and “Highest Rated” that update regularly. Seeing new or refreshed content on the landing screen of an app, based on the behaviors of other kids like them, is pretty exciting for these kids, since it’s not the same old stuff they’ve seen a million times. These kids may still gravitate toward the same group of videos each time, but they’ll love to see how the content changes. In fact, a “New Stuff” category would be pretty cool here, too.

Description

These kids won’t read descriptions as closely as the 6–8s, but they will scan for keywords of interest to decide if the video’s worth watching or not. What will be especially important to these kids is the rating shown here. As mentioned earlier, the opinions of others are fascinating to them, so they’ll use the ratings to determine whether or not they’re interested in a particular video. Since kids of this age can understand nuances better than younger children, you can use a star rating or a numerical rating here to indicate popularity, as opposed to a like/dislike toggle like the thumbs-up, thumbs-down that was used with the younger guys.

Sharing

The 8–10s love the idea of being able to share something with their friends. Including this functionality will make the app feel more personal and extensible to these guys, especially if they can share stuff they made, like video mashups or playlists.

Ratings

We talked about the importance of ratings on the previous page, but here we’re going to discuss the importance of contributing to ratings as well. Using a simple interactive rating feature, like tappable stars or numbers, will encourage kids to add their voice without a lot of work. It’s best not to allow kids much younger than 12 to review products, media, or sites via a free-text field simply because you’ll get a lot of expletives and useless single-word answers. If you want more detailed reviews, you can use a Q&A format with multiple-choice questions, but I’m not sure what the value will be in doing this, as kids (much like adults) are primarily interested in the rating itself.

Flow

While I don’t recommend a lot of in-page interruptive messaging for younger kids (simply because it takes them out of the experience), providing subfunctionality within some sort of overlay or expandable panel works well for these guys, who are all over the place. When a user clicks the Add to Playlist button in the video player, it’s okay to let him continue down this path via simple messaging and functionality. You can also let kids create a new playlist from this screen as well.

Keep messages friendly and upbeat, with specific information about what they did wrong and how to self-correct.

Form Design

Keep the form as simple and as basic as possible. These kids are probably pretty proficient with a tablet or mobile keyboard, but you want to limit the amount of typing they have to do since it can be pretty frustrating to enter data on a mobile device.

Contacts

You can let these kids share content via email or a text message. Many kids in this age range don’t have email accounts, but they do have the ability to text via a mobile phone or an iPod Touch. Whatever mechanism you use, you’ll want to limit the people a child can share with to the device’s contact list. This reduces the possibility that these kids will contact someone they don’t know by mistake and unknowingly share personal information with them.

Subject

To reduce the amount of data entry kids have to do, you can pre-populate this field with a generic subject, such as “A Video for You.” Of course, if you’re using an MMS service to send the message, you won’t even need a subject line.