When do you transition from the snaffle to a shank bit?

A rider wants to know when and how to transition her horse from the snaffle bit to a shank or curb bit.

My horse gets her tongue over the bit. Help!

A 5 year old mare gets her tongue over the bit, and needs to use one for her future career in barrel racing. Words of advice from April Reeves.

Horse dances around and won’t take the bit

How to get a busy, dancing horse to accept being bitted and bridled effectively.