Which program language should you learn second? What about Go? It is open source, easy to grasp, clean, very powerful, ultra modern, and it will look good on your resume. In the end, Go may surprise you by becoming your language of choice.
Go Exercises in Plain Language is a series of booklets designed to facilitate incremental syntax awareness. This is not a Go primer -- concepts are only introduced when needed and to assure that the student has enough tools for creating the project code. The author uses the spiral concept of learning. All exercises are simple to do, but not simplistic. The first three volumes cover basic syntax. Advanced Go programmers might not benefit from doing these exercises, unless they've been away from coding in Go and need to get back to basics.
This is the second volume in the series and it covers arrays and slices with plenty of exercises using append.
The first volume introduces variables, loops, Boolean operators, conditional statements and basic functions. Subsequent volumes will cover more advanced implementations. The first two volumes are essential background for what comes next.