Joining yarn to scrumble

I need help with this one, since I dreamed the idea up at two a.m. this morning!! ( so help needed to test it out)
If you are teaching and don’t have any variegated yarn, you could make some!!
Cut lengths of different colours and knot them together. This would be great for beginners as they would not need to worry about fastening off the ends when they change colour.
So what about the knots??
If you think as I do, then the added texture is good, although if you wanted to hide them, just push them through to the back of the work!
However, for the more adventurous you could leave longer ends when you join the colours together and tie them in a bow later.
For the even more adventurous, if you leave them long enough, you could crochet them in ad hoc afterwards to make spidery or bobbled textures. Just get creative!
Using different colours when learning Platform style is important as it is so much easier to see what is happening.
Longer lengths are probably better, shorter lengths will show just a few stitches. A mixture of lengths will produce a different effect too. Help and post results guys!!