A General Teaching Council panel was told that checks showed that some pupils had their course work altered.
The panel decided that Miss Bowen, who has already been sacked, was guilty of unacceptable professional conduct.
Miss Bowen was not at the professional conduct committee in Cardiff.
The tribunal was told she had initially denied changing the work, but later admitted she had, and was dismissed for gross misconduct.
Some mistakes had been corrected - in one case the word "higher" was changed to "lower", and in another, "wasn't", became "was", the tribunal heard.
As well as her altering words and figures, the hearing was told she also wrote lines in pencil for pupils to go over them in ink.
In all, Miss Bowen, a teacher of 12 years' experience, altered a total of 21 GCSE course work papers submitted by the 16 pupils, it was claimed.
The hearing was also told she had given the pupils so much help that their work was impossible to reassess, so they had to be assessed on earlier years and most of them were marked down.
