Open your mouth WIDE and pull your lips back like a big smile. Tongue low and forward — /a/, as in 'cat'.
Check yourself: Hand under your chin: this is the one where your jaw drops the most. Mirror: widest smile of the five.
Watch for: /ɛ/ (short e). The two are neighbours; the jaw is the difference.
◆ marks a word that does NOT follow today's pattern — Blumenfeld boxes these on the page. Teach it by heart; do not let the class sound it out and lose faith in the rule.
Say the word, have them repeat it, count the sounds on fingers, THEN write. The count is what stops a child writing the first letter and guessing the rest.