As a rule, the following conditions and exclusions apply to activities abroad.
*You should spend timing interacting with other adult speakers of English (at least some of whom should be native speakers) at relatively sophisticated, academic and/or professsional level. This excludes activities such as fruit picking; working in a factory; working in fast-food restaurants; manual farm labour without additional responsibilities; programmes run by German organisations where all the participants are German and there is limited contact to locals; working in German-language office environments; working on a building site...
*Work at the front desk of a hotel or hostel is fine; working in housekeeping in a hotel or similiar without visitor or other staff contact is not.
*Work as an assistant teacher in all types of schools counts, even if it is not the school form you are studying in Oldenburg (ie. MEd Gym students can work in primary/elementary schools). It is also fine to work at a kindergarten or pre-school.
*It is perfectly acceptable to complete an internship teaching German as long as interaction outside the classroom takes place in English.
*Work as a rugby coach or surf teacher can count under some circumstances as long the teaching and profesisonal interaction is in English.
*Work as an au pair needs to be accompanied by some form of academic or formal interaction - a second job, a part-time language course, volunteering at a school...
*Work with wildlife (esp. in Africa) can count, as long as there is sufficient interaction with locals and non-English-speaking co-workers.
*General office or volunteer work in a non-educational context is fine assuming the general criteria are met - you do not have to do something school related!
When in doubt, please contact a stay abroad advisor to check your plans in advance and complete a learning agreement!