I only have OpenOffice on my laptop (no idea which one. I just got it from the Internet)
At school they only have PowerPoint (2010). If I do an OpenOffice presentation, can I open it with PowerPoint?
Probably yes.
Only the probability is very high that everything has shifted and does not look the way you prepared it at home.
I would not take the risk
You better install OpenOffice on the school computer. Talk to your teacher if that's possible.
Many schools only use OpenOffice because it's free.
Yes, but the presentation will probably differ somewhat from PowerPoint.
Only looking is more original with the PowerpoinViewer.
Download: https://www.microsoft.com/...t%20viewer
You have to save the presentation as .ppt.
File - Save As - MS PowerPoint.
The schools should really be a bit more flexible and install these free office variants such as OpenOffice, LibreOffice and possibly also the FreeOffice softmaker on their systems.
But unfortunately a lot of people are queuing up to even consider something outside the "guideline".
