This February half term, turn master-spy as you discover how to write and uncover secret messages using a very special invisible ink: lemon juice! This fun activity comes courtesy of the lovely people at The Bar Convent, York, and should keep your children entertained during this half term when things are a little different from normal.

When it comes to sending secret messages from inside a prison, we might not expect a sixteenth-century nun would be an expert at it – but the Yorkshire-born religious pioneer Mary Ward never cared much for expectations. Learn how Mary Ward used lemon juice letters to send secret messages to her follows and have a go at your very own at home by downloading the free worksheet from the Bar Convent website.