J.I.
I highly recommend Patty Favalora. She teaches from her home year round (her pool is enclosed), although you can choose to do only summer lessons if you like. She teaches just 4 kids at a time or you can pay more for private lessons. Because she is the only teacher, there are not other classes going on while your child is swimming. She is located near Ohio & Park in Plano.
We've been going to her since my oldest was 3. He'll be 5 on Sunday and can swim unassisted all over the pool, dive, etc. He is extremely confident in the water. My 3yo just started last summer and asks to go to "Ms. Patty's house" every day, he loves it too.
Here is her contact info:
Patty Favalora
###-###-####
____@____.com