I've not used either of those two devices, apart from a brief play with a Sphero, controlled from a phone. Clearly they have a niche, but I'm not sure they are the best choices.
Robotics is obviously a huge subject, and there are plenty of simple robot platfoms available. I think starting simple is maybe best, rather than introducing the control loops and sensor feedback that is presumably present in Sphero. If you have a Sphero, then you should probably be using it as an example of current state-of-the-art for a semi-autonomous robot and explore the evolution of this technology and it's potential applications in 5 to 10 years time. Robot vaccum cleaners, surveilance drone for the elderly, that sort of thing.
MakeyMakey looks like a USB I/O (or input only) faker. In vogue nowadays as a hacking device. In the PC era, this would have been a fairly essential route to interfacing the real world to some software (as we used to with parallel printer ports in the distant past). I feel things have moved on now, and we're either using a Raspberry Pi with GPIO (and some powerful python libraries), of a micro:bit (and micro-python). So to find a MakeyMakey application which fits your course, you might want to look at micro:bit lesson ideas (where none of the sensors or LEDs are necessary). Really, though, I think MakeyMakey's scope is quite limited (unless I misunderstood). You could program it as an arduino - probably the easiest application is for data logging in a science application. Log voltages as a capacitor is charging/discharging, or temperature in a classroom, something along those lines. To keep it self-contained, maybe you'd need to brainstorm around the applications of connecting the real world to the software world again (can you spot that I'm an embedded developer?). You could take it into the security realm (never connect anything to a USB port you care about), but that's a bit of a can of worms...
If these subjects seem like a bad fit for the material you're teaching at the moment, all the more reason to try and incorporate some of it. The rise of very powerful microcontrollers (Cortex-M3 ran doom back in 2005, and is 10x smaller now), and ubiquitous wireless network connections make distributed sensors and actors just as important part of applied computing as online shopping. It's likely that the different areas will appeal to different individuals.