Classes that normally had 19 children only had five.
Head of Pahoia's junior school Gemma Grinder said only one child made it to each of her four reading groups.
"So they got one-on-one time. They loved it, especially the 5 and 6-year-old children," Ms Grinder said.
Ms Grinder said many staff were also unable to make it to school because of the crash.
At Katikati College, 22 teachers were unable to get to work.
Deputy principal Ian Nicholson had to take the alternative route over the Kaimai Ranges and principal Neil Harray said staff met early to cover classes.
Meanwhile, eight staff at Katikati Primary School could not make it and principal Andrea Nicholson said the closure caused headaches.
"Three committed staff managed the journey through Matamata - it caused chaos."
The road closure also caused a number of court cases to be called off at the Tauranga District Court because defendants were unable to make it to the city from Katikati.
The highway opened again to traffic at 1.30pm.
Omokoroa fire chief Ian Blunt said the impact of the crash meant the canisters punched through and dented the aluminum roof of the trailer unit.
Firefighters removed the canisters by cutting through the steel casing they had been stored in.
Western Bay of Plenty's Serious Crash Unit were at the scene of the accident to establish what happened but Senior Sergeant Ian Campion said it was still too early to say.