Yes — "a" is one of the first sight words taught, since a single letter can't be sounded out using typical phonics rules the way a full word can.
I saw a bird in the tree.
As the shortest word in English, "a" doesn't fit the usual pattern of blending letter sounds together — there's nothing to blend. Children simply learn to recognize its shape and sound (a soft "uh") from repeated exposure, making it a sight word by necessity rather than irregularity.
Point out how "a" changes to "an" before words that start with a vowel sound ("a dog" vs. "an apple") — a small pattern worth noticing early.
Word Wizard teaches "a" with Flash Cards, Listen & Pick, Spell It, and Write It — four game modes that turn repetition into play.
See "a" with its picture, syllables, and example sentence — with native audio.
Hear "a" spoken aloud and pick it out from similar-looking words.
Build "a" letter by letter from shuffled tiles.
Word Wizard turns sight word practice into a game — Flash Cards, Listen & Pick, Spell It and Write It, from Pre-K through Grade 5.