Jack Be Nimble is a short, old nursery rhyme. It was first time published in year 1815. But the rhyme is still popular and it is used daily in many preschools and schools in England and USA.
In this rhyme, Jack jumps over a candlestick. Be aware that this may be an inspiration to try the same for some kids. So after singing "Jack Be Nimle", you better tell the kids that they NEVER must jump over candlesticks. In real life that is just stupid behavior.