Perhaps owing to my early influences, I still consider a lightweight BASIC environment to be an excellent way to introduce kids to software development. This article focuses on BASIC-256 (previously known as KidBASIC), an easy to use interpreter for young children. More here

BASIC-256 supports a small subset of the language features found in dialects like DOS-BASIC, but there are enough supported statements to allow for surprisingly capable programs. Subroutines are supported, and the core commands are easy to learn.