A flagship principle of the alphabet is that each letter has a related or connected sound that is unique to it. These sounds occur in a very predictable manner. This helps students progress towards being able to say and understand words. This is first step in the process. After students understand the sounds that are produced, they learn how to arrange those letters and sounds to create their own words. The English language has forty-four unique sounds called phonemes, yet there are only twenty-six letters in the alphabet. This is because the English alphabet was rooted in Latin. The Latin alphabet lacked a full vowel spectrum and also lacked the sounds for Ch, Dj, Ng, Sh, and Th. We make these sounds up by chunking letters together to produce these sounds.
In some parts of these worksheets you have multiple letters that can be used to make word, but pay attention to the pictures that are provided. There is much debate as to how many letter sounds there are. It is commonly accept that there are 40-45 distinct sounds. The fact that there is debate over this, when you spell a tough word incorrectly should make you feel better. An interesting fact is that the letters "Y" and "W" can and many times serve as vowel sounds. But there are 16 consonants that have consistent sounds they are called constant consonants.