Stool in bath room

I wonder should I buy metal step stool or plastic step stool now. I am thinking to get one for the children actually. It seems quite dangerous for them to use plastic step stool in the bath room as it just too slippery in the bath room. Today my youngest daughter falls down from the plastic stool while having bath again. She is too active in playing in the bath room and always likes to climb up and down to play. Hai… I think I better get a stool with more safe for them.