This is an answer to Sylvia's blog post:
I would say from my perspective with a yes and a no (in German it is called "Jain"). It depends largely on how old the students and what is the current key content in the classroom. In classes with younger students it is certainly much better to use the customized kits of Hummingbird or littleBits. I have made excellent experience with the Arduino in classes with older students. Especially the issues of scalability was for us an important question : What does that mean, I start with the kits listed above, and use the experience later in ambitious projects on a similar hardware base. (Hummingbird and littleBits can be programmed Arduino-like). I can use different approaches to programming (switch between Scratch and Arduino programming language).
Important for a transition is mainly the question of the software in use. In the Arduino ecosystem, we use a combination of the software Fritzing, ScratchforArduino and of course the Arduino IDE.
One Thing is, you have to learn the correct use of wires and breadboards to design a proper circuit. Certainly you can not do so much wrong with adapted kits. On the other hand Fritzing has become so well-developed that many projects can be well understood. We use here mainly the Fritzing Creativity Kit.
A help in dealing with breadboards:
An intermediate step to avoid faulty wirings is the Grove system of connectors by Seedstudio. There some beginnings to incorporate this into the Fritzing-Environment:
Tthere are numerous modules with grove-connectors, which can be docked to an Arduino, it can also be integrated even for future projects in a Raspberry Pi.
Back to the Arduino-Ecosystem we have to look at the needed Hardware. The adapted kits includes matching modules (Sensors,LED's, buttons ...). The Arduino use in most cases standard electronic components.
That's from time to time a disadvantage, although 'obtaining' but can also be tackled differently.
We get these components in which we disassemble old devices with students and unsolder the relevant components. This works very well with younger classes, One Example are the well known brushbots be tinkered from old cell phones. Even in a short time, a conglomeration of components collected together, which can be used in other projects.
The decision which tool or kit you use in your classroom it's always a question of a limited available budget and to find a balance between the various approaches. I think it's useful to have a scalable hardware base in some cases, you can use with different ages of students. But the learning environment and strategy is much more important. And tools are changing from time to time.