Letter sounds -- also known as phonics -- are an extremely important part of ESL learning. This is because they are the "bridge" between spoken and written English. Speaking is a matter of understanding and emulating sounds, while reading is a matter of understanding the connection between letters and words. If someone can read extremely well, he may not be able to pronounce intelligible English, and vice versa. Effective phonics lessons provide a good foundation to keep this from happening in order to develop well-rounded ESL English speakers.

Focus on one letter sound at a time. It is important to understand the difference between a letter and a letter sound. This is particularly true for vowels, each of which has many sounds depending on their usage and context.

Teach a letter through simple words. The students may not necessarily understand all of the sounds in the words, but if you teach "cat," "car" and "cave" at the same time they will be able to understand the significance of the "c" sound due to the fact that it's the common denominator between the three.

Have students repeat words in a variety of contexts. Start by just saying the word and having the students repeat it back to you. This will give them an idea of the right way to say it and start setting it in their brain.

Move on to activities that apply the sound. Games are an excellent way to do this. For example, you could draw pictures of the "cat," "car" and "cave" on the board, and then line up two students. Point to one of the pictures and award a point to the first student to say the word clearly and correctly.

Advance to another letter sound once most of the students are saying the first clearly and confidently. However, you should not assume it is completely set in stone. Rather, you should constantly review, referring back to old phonics sounds in games, activities and lessons in order to reinforce the learning.