Hello antanana,
At Wikimedistas de Uruguay we've run two contests that I think suit your description:
1- Click to the school: https://meta.wikimedia.org/wiki/Event:Click_a_la_escuela -- We invited people to submit photos of their schools, after uploading the open dataset of all the Uruguayan schools into Wikidata. This happened near a few trainings we were doing with teachers so it was a good opportunity for them to try. We got some quite amazing pictures.
2- Foto.Física: https://meta.wikimedia.org/wiki/Event:Foto.F%C3%ADsica_2024 -- In this case, the Society of Physics of Uruguay has been running this contest for quite a while now (I think over 10 years) and this year we co-organized the contest using Wikimedia Commons as the platform. They were a few things that we could have worked better (for example, the category system), but overall it was an interesting experiment.
Happy to talk more about them if you're interested.
cheers,