The social sciences classes were tasked to find information about each of the 110 soldiers, and the maths students will be making a plan for how the crosses will be placed in the ground.
The English, French and Maori students will write poems and the winning poem in each language will be read at a commemorative ceremony on April 22.
Each cross will bear a soldier's service number, rank, initials and surname.
People walking past and visitors to the school will be able to see the display, situated near Cameron Rd.
Mr Armstrong said when the crosses were completed they would be put in place on the first day of next term and a kaumatua would be asked to give a blessing.
A minister from St George's Anglican Church will lead the commemorative ceremony on the Wednesday before Anzac Day, which will also be attended by RSA representatives.
Art student Shireen Harper was helping paint crosses when the Bay of Plenty Times visited the school yesterday. She said WWI helped form New Zealand's identity.
"I've been to Gallipoli. I used to live in Egypt, we used to live near Maadi where the soldiers trained before they left for Gallipoli," she said.
"We went for a holiday to Turkey and visited Gallipoli and all the memorials. It was really emotional. It's a very desolate place. There's nothing there except the memorials."