It won’t be awkward. People miss lots of opportunities because they don’t ask. Your teachers want to help. Most people want to help and if asked will help you pursue your goals.
You email your teacher, tell them that you are planning on applying for various writing programs that require a letter of recommendation, and would they be willing to write one on your behalf. Would probably attach your writing sample as well and maybe a 1/2 page bullet point of your GPA, honors etc. if any to help them write.
Here is the key: Give them LOTS of time. At a very minimum 2 weeks (with lots of apologies for the late notice), more like 4-5 weeks. After they write it - you write them a handwritten thank you card (always nice to throw in a $10 Starbucks gift card). and then after you go to whatever program they wrote a letter of recommendation for - follow up and tell them how much you learned and appreciate their assistance.
You may want to go back to these teachers for future recommendations. You want to make it as easy as possible and make sure they know that their recommendation was very appreciated.