They have just had a Treaty of Waitangi workshop with Jillian Wychel and David James and spent four nights on the Whanganui River. Their Ki Tai river guides had them welcomed onto a marae every night and farewelled next morning.
"We've got a special relationship with the iwi and whanau that runs us down the river and it's a transformative experience for the students," Mr Roberts said.
Today the students are helping volunteers at Gordon Park Scenic Reserve.
Next week they start internships with groups such as Bird Rescue Wanganui, Bushy Park and Wanganui Intermediate School They will also have classes held at the Tupoho Community Complex.
During their three weeks in the South Island they do a tidal pool study at Kaikoura with Canterbury University, walk the Heaphy Track and help out in the red-stickered zone of earthquake-hit Christchurch.
Mr Roberts has a "heartfelt attachment" to Christchurch. He and his wife were leading a group of students there during the February 2011 earthquake.
"We were 3km from the epicentre in Sumner, with students spread out all over the city. It was a long few hours waiting to see and hear back from them."
One was interning at a primary school above the Christchurch bus exchange, and helped pupils out of the collapsing building. Two others were in Lyttelton, where bus service to the city was cut off.
"They walked over the Port Hills to the house in Sumner and knocked on the door three hours later, and boy were we glad to see them," Mr Roberts said.
That year the students were all evacuated back to Whanganui, where an alternative programme was patched together for their remaining 10 weeks in New Zealand.
It worked so well that since then the students have spent most of their time here, with just three weeks down south.
Mr Roberts' wife Marcie said students' experience was deeper and richer for spending more of their time in a smaller centre.
"We think this is an amazing town with amazing resources, and we couldn't be more thrilled to base our programme here," Mr Roberts said.
