The Avoda of Sefiras HaOmer

A father spends two hours on a bus with his screaming three-year-old, on his way to a specialist, and is quietly aching over the learning he gave up. Then someone says one sentence to him that changes how he sees it all. It connects to a puzzle in Sefiras HaOmer. Why do we count from the Korban Omer, an offering named for a measure of grain, and not from the first day of Pesach? The Chinuch's reasoning points to what these weeks are meant to be, and why Shavuos carries the name it does.