Depends on how young. Logo if they're in elementary school; it was designed for children of that age. A large number the students I teach started with Logo as children and went on to learn other languages.
1. https://people.eecs.berkeley.edu/~bh/v1-toc2.html
2. https://people.eecs.berkeley.edu/~bh/v2-toc2.html
3. https://people.eecs.berkeley.edu/~bh/v3-toc2.html
(edited for better display of list of links)