This is a good first chapter. The ending gives enough information of things to come, but stays open so that I want to read on.

I saw in your portfolio header that English is not your first language, so I am going to point out a few areas where you have spelling and grammar to fix.

Anne on her way saw Olivia sitting beside the window dumbly.
[On her way, Anne saw Olivia sitting dumbly beside the window.]

he asked[,] "Would you like to join us?

Athora's map[,]" he whispered.

Jack had seen his teacher hiding the map[no space here] .
The extra space at the end of sentences before the period happens several times in the whole piece. You need to take those spaces out.

"Shh..."and the[y] both paused. "Someone may eavesdrop [on] us.

The feeling of awe acquired her bringing butterflies in her stomach .
The feeling of awe brought felt like butterflies in her stomach.

As you see, there are a few areas that can use a little clean up. It reads like a fun adventure starting off. I hope you enjoy writing it and will keep going.