BLOOMINGTON, Minn. - On a pond near Richardson Nature Center in Bloomington, several 4th graders got to see and try ice harvesting and learn the history of the industry.

For about a century, Minnesotans harvested ice. Not for ice castles, but for food preservation.

"It was totally essential, that was how you preserved your food. Until electricity came along and people could afford the electric refrigerator," said Tim Graf, Ice Harvesting Historian with Three Rivers Park District.

This year, the ice is extra thick.

"I've been doing this for 20 years and it's been 10 years since we've had ice 15 inches thick," said Graf.

Blocks that were cut from the ice weighed around 220 pounds, back in the 1870s this would have been worth about 50 cents.

"The farmers, carpenters, a lot of people didn't have much work in the winter. So that gave them a little extra money to sustain themselves until the work season came along again," said Graf.

For the ice harvesters, they could extract a lot of ice from a small area.

"The area of a football field is about an acre, you could get 10,000 tons of ice out of there," said Graf.

Ice harvesting changed our diet, allowing us to preserve food much longer than it normally would have. While we don't do it today, it gave these students a hands-on history lesson.