Christ's Pieces is not owned by Christ's, however as this park is right outside the Second Court side gate, it's really easy to use as a Christ's student.
Christ's Pieces is a grassy area of 3.2 hectares with paths across it. It has outdoor table tennis tables, four hard tennis courts which you can book, a bowling green and a play park. There are plenty of benches and a little memorial garden for Diana, Princess of Wales.
Along the Christ's side, there is a path called Milton's Walk, which leads from the Second Court Side gate to King Street in one direction, and to St Andrew's Street past a Tesco Express in the other direction. One of the diagonal paths leads towards the Grafton Shopping Centre and Vue cinema, and another towards Midsummer Common and the river Cam (ideal if you want to get straight out of Christ's into nice places to walk or run). Meanwhile, the bus station is on southern edge of Christ's Pieces, which is very convenient!