Small and Portable

This works well, it just requires quite a few extra steps to get it working. You can't really think of this as a karaoke unit, but it is what you can use if you do not have blue tooth available, as that is a requirement on most of the portable karaoke microphones being offered today.
This one is completely wired. You can hook your phone up to it and a set of headphones for personal listening. You can hook a phone or computer up to it and a apeaker. Using the phone for streaming music, and the speaker for output. It does not have its own output, ie speaker. It works as a receiver/transceiver only, from what I can figure out. You cannot turn it on and use it alone. 
When I plug my phone into the aux port, and then a set of headphones in, I can hear the music from my phone in the headphones. When I sing into the microphone, I can hear it through the headphones. The same process with speakers. Now, if you have people listening, they will still hear the music from my phone and me singing, but not like through a microphone, if that makes sense? They will only hear the microphone amplification if you plug a speaker in. 
While these work well, if you adjust the volume, it does not adjust your voice volume, only the streaming music volume. The echo adjust the echo of your voice. 
I feel that while these work as karaoke, I think they're built more for things such as podcasts or speaking and amplification. But, if you don't mind listening to the music, and your child singing, but really wish to skip what the microphone will do to the volume, plug in a set of headphones for them and let them go.