Answer
Joachim had six children. His first wife, Anna of Brandenburg, bore him five children: John Frederick, Elector of Saxony, Frederick II, Elector of Saxony, Maurice, Elector of Saxony, Sigismund, Duke of Coburg, and Anna of Saxony. After Anna's death in 1547, Joachim married Elisabeth of Hesse and they had one child together, John, Duke of Saxe-Coburg.