Little Thunder was writing in his farm diary. "Today I was hoping in the paddock," he read out proudly.

Suzy looked over his shoulder. "Hoping? Were you wishing for something?"

"No, I was jumping!" said Little Thunder.

"Then it's hopping, with two Ps," said Spike. "Hope and hop are different words. When you add a suffix like I-N-G, the spelling rules change them in different ways."

Little Thunder groaned. "Rules? Spelling has rules?"

"Lots," said Suzy. She drew a chart on the shed wall with chalk. "Rule one. If a short word ends with one vowel and one consonant, like hop, you double the last letter. Hop becomes hopping. Run becomes running."

"Rule two," said Spike. "If a word ends in a silent E, like hope, you drop the E. Hope becomes hoping. Bake becomes baking."

Little Thunder scrunched up his nose. "So hopping is jumping, and hoping is wishing."

"You've got it," said Suzy.

Dublin the cow poked her head in the door. "What about my favourite word? Happy."

"That's rule three," said Spike. "If a word ends in a consonant and then Y, you change the Y to I. Happy becomes happier. Carry becomes carried."

"But not before I-N-G," added Suzy. "Carrying keeps its Y."

Little Thunder tried it out. "Swim becomes swimming. Shine becomes shining. Cry becomes cried."

"Perfect!" said Spike.

Little Thunder picked up his diary and crossed out his sentence. He wrote it again carefully. "Today I was hopping in the paddock. I am hoping for more hopping tomorrow."

Dublin laughed. "That's the happiest sentence I've ever heard."

"Happiest," said Little Thunder. "Change the Y to I!"