The air traffic control service, Nats, has extended its ban on flights until at least 0100 BST on Tuesday because of the Icelandic ash cloud.
Hanham Abbots Junior School, in South Gloucestershire, said eight members of staff were stranded.
And a Bedminster teacher who is stuck in Australia has used a webcam to lead a school assembly online.
Hanham Abbots is expected to reopen on Tuesday when five teachers return.
Acting deputy head teacher Tracey Serle said the five members of staff had gone to Lithuania for an organised event and had been due back in the UK on Friday.
"As a result they've been making their way across country for the last few days, and our head teacher drove across on the ferry yesterday to collect them and brought them back this morning," Ms Searle said.
She added that three teachers would not be able to make it home in time for Tuesday, but cover would be arranged for their classes.
Joanne Wallace, a Year 5 teacher at Parson Street Primary School, used a live webcam to talk pupils through her experience of being stranded in Sydney.
Head teacher Mark Lacey said the school had been "quick to make this into an opportunity to enhance learning about life in other countries".
He said another teacher was returning from Egypt by bus.
Fifteen members of staff from Bristol Metropolitan Academy, in Fishponds, are also stranded abroad.
A spokesman for Nats has said the cloud of volcanic ash is now covering all of the UK.
Passengers due to fly from Bristol Airport are advised to contact their airline for the latest information before they set off.