Seek out a mentor not a tormentor. Are the swimming skills taught age and developmentally appropriate. Infants and toddlers do require a high level of trust. Are children throwing up from fear or from swallowing excessive amounts of water. Be wary of the use of intimidation to persuade you that it is your baby's responsibility to safeguard itself against drowning.
Fear can easily cloud a parents better judgment, potentially derailing the higher course of action.
This is of course a testament to patience and long term perseverance in the learning process. This can indicate a lack of education to parents and care givers in regard to the comprehensive approach to pool and water safety. Fear and intimidation are often amplified in the name of safety to justify the use of force to prematurely and repeatedly submerge or back float an unwilling child. Crying is not a prerequisite to learning how to swim. This should be a happy experience.