The following awk script should solve your probelm provided you manually add the School heading yourself or if that remains same add it as BEGIN { printf "School" } in below example.
$ cat input_file 
Mark,Texas High, Dallas, k-5
Steve,SA high,Antonio,k-5
Adam,Plano tech,k-5
$ awk -F, 'BEGIN { sep = ""} { printf("%s%s", sep, $2); sep = ","}' < input_file 
Texas High,SA high,Plano tech
solved How to get the specific data in a file and direct its output to to new file?