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With STEM education being more prevalent these days, I was curious about a number of toys on the market geared towards teaching kids how to code. With all the options out there, which toy is the best investment? In the interest of scientific inquiry, I picked up four popular toys that support both simple block-based coding as well as advanced coding languages and gave them a try.

The Robots

Dash is an adorable little robot that was created by Wonder Workshop. It also has a little sibling, Dot, which is a non-mobile version of Dash. The two robots can be programmed to communicate with each other. The first thing you will notice about Dash is its giant white LED eye and the cheery “Hi!” greeting when you turn it on. Not only can the Dash move directionally, but it can turn its head and react to voices and claps. It also has one colored light on each side of its head and one colored light below its eye. As far as peripherals go, Dash has three embedded microphones for sensing sound, two infrared (IR) sensors for sensing distance, and a speaker to play sound. Dash can be programmed via an iPad or Android tablet.

Sphero is the simplest robot of the group. It does one thing, but it does it well: roll. The entire ball lights up with RGB LEDs which can be controlled independently from the motion. Sphero is also surprisingly fast – it can reach a top speed of 4.5 miles per hour. There is also a neat clear version of Sphero aimed at education. The Sphero doesn’t have any external sensors per se, but it can detect impact and being picked up thanks to an internal gyroscope and accelerometer. When you first turn on Sphero, you have to do an orientation calibration routine so it can understand where you are in relation to the robot. Sphero can be programmed by an iOS (iPhone/iPad/iPod Touch) or Android device.

The most complex of the four robots is the LEGO Mindstorm EV3. This kit comes with a programmable brick, a handful of sensors, two motors, and 550+ LEGO Technic parts for creating just about anything you can imagine. To build a LEGO robot, you first build a LEGO structure then attach the programmable brick and various sensors or motors depending on what you want your robot to do. The sensors connect to the programmable brick via connector cables and the robot is programmed with a Mac or Windows computer. Although this method can be very time-consuming, it also seems to be the most flexible. There are many books and websites available to walk you through different robot builds and corresponding sample programs if you’re not quite sure where to start. For this evaluation, I built the standard TRACK3R robot from the Mindstorms manual using the infrared sensor for distance detection.

Another extensible robot is Makeblock’s mBot. Makeblock’s robots are built on top of an open source Arduino-based platform. The mBot is similar in spirit to the LEGO Mindstorm: you can combine a number of sensors with aluminum structure parts to come up with just about anything you can think of. Makeblock also offers many robotics kits with varying degrees of complexity, such as a 3D printer kit and a XY plotter kit (which can also be converted to a laser engraver). The mBot kit is specifically geared towards STEM education and comes with a number of sensors, such as an ultrasonic sensor, an infrared receiver, and a line follower as well as some on-board color lights. All robots on Makeblock’s platform can be programmed with a Windows or Mac computer using either their mBlock software or the Arduino software.

The Test Course

For the evaluation, I set up a simple evaluation course and assessed how hard it was to make the robot accurately navigate the course. The course consisted of these simple steps:

• Go straight until it senses/runs into the first barrier
• Flash the lights
• Turn right
• Go straight until it senses/runs into the second barrier
• Flash the lights
• Turn left
• Go straight for a short distance
• Spin in a circle three times
• Flash the lights

Programming the Robots

For each robot, I used their block-based programming language to program the evaluation course instructions. For the uninitiated, block-based programming is a process where you drag block-like icons on a screen to create a chain of commands that represents a simple program. This method was widely popularized in education circles by MIT’s Scratch. By simplifying coding this way, people can become acquainted with the core concepts of programming without having to worry about the nuances of specific programming languages. Once someone is familiar with the basics of programming, it’s easier to understand more complex programming issues such as language syntax and scoping.

Dash

To program Dash, I used the accompanying iPad app called Blockly. The Blockly app has a several commands on the sidebar. To add a command to your program, simply click on the type of command you want to use, select the command you want and drag it over to the program area. The commands snap together to make a long vertical chain of commands, which are then executed when you click the start button. Blockly also supports using a few simple variables in the code if you want to keep track of things like the number of times Dash encountered an obstacle.

One thing I really liked about Blockly was that many of the options were presented in terms of real-world values. So, for example, when you programmed Dash to move forward, you could select the distance in centimeters.

All in all, the Blockly app was simple and easy to use. Connecting to the robot was as simple as holding down the robot icon until a green progress bar was full, indicating that the connection had been established. The only real issue I had with Blockly was that the app crashed on me a few times while trying to program Dash. This was not a serious deal breaker as my program was intact when I reopened the app.

Sphero

To program Sphero, I used the SPRK app on my iPad. Just like Dash, there are groups of commands at the bottom and you simply drag the command you want to use in the program and snap it into place. Once your program is ready, click the run button and Sphero will start executing the commands. The SPRK app allows you to modify preset variables such as speed and heading and well as create your own custom variables .

The SPRK app uses a different programming paradigm than the other robots. Instead of reacting to a single event, like having an obstacle in front, there is one block of code that is executed for every time a given event happens. This made programming Sphero a little abstract at times and could be hard for someone new to programming to understand.

I didn’t particularly like the SPRK app that much. I found the large amount of unusable space on the right annoying considering that I could not rotate the app to use the space. I also found that the SPRK app did not give simple feedback if there was something wrong with a program. For example, I got this somewhat cryptic error when trying to flash the lights when a collision occurs:

That being said, one thing I really did like about the SPRK app was that at any time you could click on a code icon in the upper left corner and see how your block-based code translated into their Oval coding language. Being able to look at the underlying code could be really useful when transitioning to writing code in the corresponding programming language. I was also pleased with how simple it was to connect the robot to the SPRK app. The app would automatically establish the connection after the initial Bluetooth setup.

Mindstorms EV3

I programmed the EV3 using the corresponding Mindstorms software on a Mac computer. With this software, blocks are laid out horizontally and can be broken into separate lines to help with readability. I connected my EV3 to my computer via a Bluetooth connection, which not only allowed me to program the robot remotely, but also allowed me to see the real-time sensor values in the lower right corner. Executing a program was as simple as clicking the download and run buttons in the lower right corner.

One thing that is initially frustrating about the Mindstorms software is that, much like LEGO manuals, they don’t really use words anywhere. At times it’s not intuitive on how certain blocks should be used. Additionally, since the TRACK3R robot used tank treads, there was no simple “move forward” command, but rather I had to specify the power and direction of each tank tread. Movement is time-based, so there’s no simple way of translating a time into an actual real-world distance.

Even though the Mindstorms software feels a bit abstract at times, it is still pretty powerful. The software supports custom variables and also allows you to build custom blocks using the My Block Builder feature of the software. You can also add comments to your program to help you keep track of what you are doing. Additionally, the software allows you to add your own sounds and images to be used by the robot. One interesting feature of the EV3 is that the programmable brick has its own program editor so that you can modify the program on the robot without having to use the computer. As far as connecting the EV3, I found the Bluetooth connection to be a bit hard to establish at times. To fix this, I had to reconnect the EV3 to the computer via a USB cable just to reestablish the lost Bluetooth connection.

mBot

Makeblock has their own derivative of Scratch called mBlock. In fact, it still has many of the same elements as Scratch, so you can make a cartoon panda dance on your screen while your robot is moving about. I found this handy for understanding what the robot was doing at times – I could just have the panda display the sensor values on my computer screen while my robot was running. I programmed mBot using the mBlock software on a Mac computer, connecting to the robot using a 2.4 GHz wireless serial connection. Connecting to the robot was as simple as selecting the connection type I wanted to use in the Connect menu.

The mBlock version of Scratch also has an Arduino mode, which allows you to see how your mBlock program translates to Arduino code. In order to use this mode, you cannot have any non-robot sprite commands in your program (so no dancing pandas). Much like Sphero, this helps you to visualize how the blocks translate to Arduino code. Unfortunately, the generated Arduino code can be a bit cryptic, especially for someone who may not be used to staring at written Arduino code.

I thought that the mBlock software was really well designed and powerful. Those who have used Scratch before will find the software very easy to use. The window views are configurable so can you hide or resize different windows of the software. Like the Mindstorms software, mBlock allows you to create your own blocks or create custom variables for storing data. The mBlock app did crash on me a few times but I was easily able to reload my work from a saved file.

Evaluation

Here is a video of how each of the robots performed on the evaluation course:

Of the four robots, Dash was the fastest and easiest to program. The Blockly app was intuitive and Dash consistently executed the course as expected. The only issue I had with Dash is that it couldn’t navigate well on a rug.

The EV3 also made short work of the obstacle course. It took a bit of trial and error to figure out the exact motor settings for some of the tasks like turning. However, once the program was written, it consistently navigated the course without issue.

Sphero fared the worst of the four robots. Writing the Sphero code in an event-driven model felt somewhat unintuitive when compared to the procedural methods used by the other robots. Also, because Sphero really doesn’t have a front, the robot had to have the orientation calibrated each time I picked it up and reran the course. This quickly became annoying. Slight variances in calibration caused Sphero to veer off in different directions. It took multiple attempts to get the robot to execute the course correctly.

I really wanted to love mBot, but at the end of the day there were some issues with it. First, for some reason, the power to the wheels on my robot was not even, so my robot would always slightly veer to the right. A thorough inspection found no obvious reason for this and posts on the Makeblock forum showed that other people were experiencing the same issue with mBot. Second, the ultrasonic sensor readings were not normalized at all, so unexpected variances in the sensor readings sometimes caused the robot to prematurely turn. These issues made the evaluation runs far more frustrating than they should have been. Just like Dash, mBot also had issues navigating on a rug.

Conclusion

All in all, these are all great toys and any one of them would be an asset in getting anyone (especially kids) interested in programming. Dash was the easiest to use so I think it would be a great first robot for anyone, especially a younger child. The major drawback is that since most of the hardware was fixed, I could see this robot getting boring after a while. Furthermore, since Dash currently only supports programming languages with complex syntax like Objective C and Java, it would be harder to transition from the Blockly block-based programming to a full programming language.

I think the Mindstorms is the best option for people who want to have a platform on which they can grow. The LEGO hardware and software worked as expected without any issues. The Mindstorms software can be a bit confusing at first, but once you get past the initial learning curve, it’s very powerful in what it will allow you to do. As it’s been around the longest, it has lots of support material and has support for many programing languages, some of which are easier to learn (like Python). The major drawback to the EV3 robot is the high price point, which may not make it an ideal starter robot while you are still gauging your interest in coding.

The lower price point and great mBlock software still makes the Makeblock mBot kit an attractive option. My hope is that some of the initial kinks in the platform may later be worked out. It may be wiser to try a different Makeblock kit, like the slightly more expensive starter robot kit which comes with tank tread instead of wheels and a Bluetooth adapter which allows the robot to be manipulated through a mobile device. Much like Dash, the Makeblock robots can only be programmed with the complex Arduino language, which could make the transition to a full programming language more difficult. Fortunately, the Arduino mode in the mBlock software can help with that translation.

Comparison Chart

	Dash	Mindstorm EV3	Sphero 2.0	mBot
Price	$170	$350	$130	$79
Age Range	5+	10+	8+	8+
Power	Rechargeable battery via micro USB	6 AA Batteries, rechargeable battery pack (sold separately)	Rechargeable battery via dock	4 AA Batteries, rechargeable battery pack (sold separately)
Run time	About 5 hours	Varies on configuration	About 1 hour	Varies on configuration
Connectivity	Connectivity iOS (iPad) and Android via Bluetooth, Computer via USB (future)	Computer via USB, Bluetooth, WiFi (adapter not included)	iOS (iPhone/iPad/iPod Touch) and Android via Bluetooth, Computer via Bluetooth	Computer via USB or Wireless Serial, WiFi (adapter not included), Bluetooth (adapter not included)
Beginner Programming	Blockly App	LEGO Mindstorms EV3 Software	SPRK App, Blockly Beta (via Chrome Browser), Macro Lab App, orbBasic App	mBlock Software
Advanced Programming	Objective C, Java (both still in private alpha phase)	Ada, C/C++, Python, Java, C#, Perl, VisualBasic, Lisp, Prolog, Haskell and more	Objective C, Swift, Android, Python, Ruby, Arduino, Node/JavaScript and more	Arduino
Included Sensors	Infrared, microphone/sound	Infrared (and tracking beacon), color/light, touch	Internal gyroscope and accelerometer	Infrared (and remote), ultrasonic, line follower
Optional Sensors	None	Ultrasonic, sound, gyroscope	None	Accelerometer, compass, light, passive infrared, temperature, sound, touch
Sounds	Yes (fixed set)	Yes	No	Buzzer only
Lights	Front and side RGB lights, white eye light	Red/Green/Amber LED on power brick	One RGB light	Two RGB LEDs on board, many RGB LED modules (sold separately)