England's General Teaching Council found Sandra Parker, who taught at Doddington primary in Kent, guilty of serious professional incompetence.
The mistake was one of a series revealed at the disciplinary hearing in Birmingham this week.
Mrs Parker, who did not attend the hearing, said in a brief statement: "I am no longer teaching and I do not intend to teach ever again."
The disciplinary hearing was told that she had fallen seriously short of professional standards.
She joined the school in 1988 as a supply teacher and later became full-time, teaching years 1 to 4.
The 54-pupil school had three teachers, and Mrs Parker was also a staff governor.
Janet Harris, who joined the school as head in 2000, said there were concerns about the standard of Mrs Parker's teaching in 2001.
Several parents made verbal complaints and one couple withdrew their child from the school.
In January 2001, Mrs Parker was offered support including lesson observations and target-setting.
On one occasion the head came out of her office after hearing a commotion which she believed to be an unsupervised class. On further inspection, she realised Mrs Parker was lining her class up for PE but could not control them.
In one class observation, the head noted pupils were restless and became disorderly while Mrs Parker attempted to read a book to them. One child sat on a chair trying to cut his sweater.
After Mrs Parker failed to significantly improve and met only four out of 18 targets, the school began formal competence proceedings in April 2004.
She said that she had mistakenly sent pupils' assessments to Germany and was issued with a written warning on April 27, 2004.
Mrs Parker resigned with effect from August 2004 before the conclusion of the competence proceedings.