Harold and the trust have been teaching Far North children about health and nutrition from the mobile classroom since 1996, Ms Henderson saying the giraffe had become an icon.
"We talk to parents now who remember Harold," she said.
"As a teacher sometimes you just don't get time in the classroom to look at those topics that are really important. But this is coming from the outside into the school, and the kids sit up and listen because Harold is known."
The Far North's classroom, one of the oldest in the country, visited 80 schools every year, and the trust had been trying to save money for the upgrade.
"We need to pay our educator," she added. "We do a lot of kilometres, and we have to pay for the fuel and maintenance, and the truck that pulls it. So money gets eaten up with that before we get to saving money for the upgrade."
The trust had organised a night with Nigel Latta on May 14 to fundraise. Tickets will be on sale through Kerikeri's Turner Centre, or donate by contacting Ms Henderson at dianesh50@gmail.com or phone (021) 407-015. Ms Henderson said it would be "so amazing" if Northland children were able to enjoy the upgrade.
"The messages we give are so important, on healthy living and making good choices, and to be able to go in and see things happen and touch screens makes it more memorable for them," she said.