This happens because Pepper doesn't dissolve or mix into water. Adding soap breaks down the surface tension of the waters 'skin' and as the water molecules spread out away from the soap, it brings the pepper with it.
I learnt that dishwashing liquid works best because the pepper spread away the fastest. On the other hand, Hand Sanitizer is not as good because it spread the least.
My favourite part was dipping my finger in the water because it was satisfying to watch. I also liked covering my finger in the soap, hand sanitizer and dishwashing liquid because it felt weird and I loved it.
It was difficult not to let the soap, hand sanitizer and soap fall in because it would ruin the experiment. So I tried not to but it fell in on the last one because soap was slippery and it fell of my fingers.
Next time I would try not to let it drip because the soap fell of my finger and fell in and it kind of ruined the experiment by pushing the pepper before I put my finger in. I would also look for a stronger hand sanitizer to see if it would make a difference.
Here is my Slide:
