ESA and ESA Kids
I would allow the children some autonomy here while using ESA Kids. I would hand them out an iPad and let them have some fun exploring the many great resources here. In the older classes, I would ask them to report back to their neighbour about some of the things they learned.
Astronomy picture of the day
This would be a brilliant resource to use as a prompt for discussions around Space Week. I would display the picture of the day each morning as the children file in and they could discuss what they see with their classmates before school starts.
Stellarium-web.org
I find this website brilliant for displaying the night sky in the classroom, which is obviously impossible to do outside on a school day! The children would find it fascinating to stargaze and pick out some of the constellations and stars after teaching them about this topic beforehand. The fact you don’t need the internet is also a great benefit.