Extracurricular activities for Children (Strasbourg)

Hello everyone,
My family and I will be relocating from Barcelona to Strasbourg in the next couple of months. We have started the process of getting our 4 year-old twin daughters into school, but have noticed that there are no classes on Wednesdays or after 4:30pm. Could you reccommend some sites or places I can address that offer extracurricular activities fro children with working parents, who can't afford to have them home on Wednesdays and so early in the afternoon?
Thanks very much in advance. Any help is much appreciated.
Regards from sunny Barcelona,
Montse