I have Hundred Weight pumpkin seeds and intend to try and grow some
whoppers with the kids this year. Does anyone have any tips on growing
giant pumpkins they'd like to share?

I have a small amount of experience with this. Nearly 25 years ago,
I grew several 'Atlantic Giant' pumpkins. I put lots of composted (and
a small amount of fresh) horse manure in a deep hole under the plants.
I also watered regularly, and thinned the pumpkins once there were 2 or
3 to a plant.

Especially important is mulching around the plant, but you don't want
to put straw right up where the leaves join the plant. The plant will
put out additional root systems at these areas which will help give
additional moisture and nutrients to the plant. It will also help
anchor the plant against damaging winds.

I ended up with a 263 pound pumpkin, which won 1st at the county
fair, and would have taken 1st at state if I had been able to get it
there that year. I've always wanted to grow another huge pumpkin. From
what I've read, these are actually squash, but most folks treat them as
pumpkins.

If I tried it again, I would use drip irrigation and a timer, to make
sure the plant got optimum amounts of water.