"Penjelasan guru saya sangat pendek."

Translation: My teacher's explanation is very short.

[glhaynes90]

"So" isn't a great translation for sangat here. "Very" or "really" would be more typical

[dont_tread_on_me]

Seems like they fixed it.

[BarefootB]

penjelasan can mean 'lesson' as well so this should not be considered incorrect either

[Chiliem]

Also "My teacher's explanation is very brief"