HELP!!......Kitty thinks the bathtub is her litter box

I just got an 8-week old siamese kitten on Sunday. I've been keeping her in the bathroom at night & while I am at work until I know that she is used to using her new litter box. The first 2 days she pooped in the bathtub, so I called a friend for advice and she said to put the litter box in the bathtub where she kept going. TA DA!! It worked (the first time) but last night she did go again the litter box but twice next to it, in the bathtub as well. My parents are coming to visit from out of town this weekend...What can I do to get her to stop?

She is pretty young and may not yet understand the litter pan. Have patience with her, and provide her with multiple small boxes (I use those throwaway foil cake pans you can buy at the grocery store quite cheap) for kitties and their first litter pan. I would be thankful that she is pooping in the bathtub (quite easy to clean) and not the carpet. She is also more than likely a bit stressed at being away from mom and siblings so young. I would be more concerned about cat litter in the drains, then the kitten pooping in the bathtub.

She was supposedly litter trained before I got her, but then again, I teach preschool so I know that major transitions can cause little ones to regress in things like potty training. I got the flushable litter from arm & hammer, so far she has managed to not get hardly any litter in the tub. I'll try the smaller litter box idea. Thanks for the suggestions!