What grammar school did Isaac Newton attend before Cambridge?

Before Cambridge, Isaac Newton attended The King's School, Grantham, a grammar school in Lincolnshire where he studied from about 1655 to 1660.

Newton entered the school at roughly age twelve and lived in Grantham with the family of William Clarke, an apothecary. The school taught Latin and Ancient Greek, while Newton's private interests extended to drawing, mechanical devices, clocks, windmills and sundials. He was not initially regarded as an outstanding pupil, but he eventually rose to the top of the school.

In 1659, Newton's widowed mother withdrew him from school and brought him back to Woolsthorpe, intending him to learn estate management and become a farmer. Newton disliked farm work, and his former headmaster Henry Stokes, together with Newton's uncle William Ayscough, persuaded Hannah Ayscough to send him back. Newton completed his schooling before entering Trinity College, Cambridge, in 1661.