"Mommy!"

Sheldon heard his four-year-old daughter screaming from her bedroom. He sat up in bed, glancing at the clock on his bedside table. 10:47, it blinked.

"Mommy!" she yelled once more.

Sheldon stumbled out of his bed and ambled to Mia's room. She must have had one of her nightmares again. He was empathetic towards his little girl, as he was also prone to night terrors. He just wished that she would call out to him instead of Amy once in a while.

Just as he opened her door, she screamed again. "Momm-"

"Shh, Mia, honey," he interrupted her, sitting on the edge of her bed. "Mommy's working late tonight," he explained as he turned on her lamp, illuminating the pale yellow walls. "What's the matter, dolly?" he asked, wiping the tears from her little heart-shaped face.

A clap of thunder jolted Mia and she pressed her face into Sheldon's side.

He wrapped her in a hug. "Oh, Mia, baby," he whispered into her thin, straight hair. "Here," he said, slipping under her patchwork butterfly comforter and propping himself up against the headboard. He invited her to snuggle into him and she happily obliged. "So," he started, running his long, spidery fingers through her hair. "Tell me what I can do to make you feel better," he said.

Mia said nothing, but buried her face in Sheldon's chest as another flash of lightning and bolt of thunder broke through.

Sheldon sighed and rubbed his hand in circles on her back. "Okay, let me try that again. What would mommy do if she were here, hmm?"

Mia sat up and sniffled. "Last time, she told me that there was a surprise birthday party in the sky," she said, looking up at him with those big green eyes he'd fallen in love with in her mother. "And the lightning was just the birthday boy or girl walking in and turning on the lights."

Sheldon was glad he had Amy to make up such stories. He couldn't create something like that in a million years. He rested his cheek on the top of her little head. "And what is the thunder?"

"Well," she sighed. "Mommy said that- " she jumped as another bolt shook the two-story house. "Mommy said that the thunder was just the guests jumping out from behind the chairs and couches."

"Ah," he said with a small smile on his face. "And what about the rain?"

"I don't remember," she said. "Can you think of something?"

Sheldon stiffened as those big eyes met his again. "Well," he pondered, searching his thoughts for anything relevant. "The rain is... the birthday boy or girl crying because they're not a fan of surprise parties."

The tall man was not great at reading facial expressions, but he could tell that Mia was unsatisfied with his answer.

"Mia?" he asked.

"Uh huh."

"What I was little, I was absolutely terrified of thunderstorms," he admitted.

"Really?" she asked, her eyes wide with wonder.

"Oh yes," he conceded. "But do you want to know how I faced that fear?"

She nodded her head furiously. Sheldon chuckled into her hair. "Well, what I would do was remind myself why thunderstorms happen and how they really work. Knowing the science helped me feel better. Now we can stick with mommy's story if you want..." he said as the power went out. Mia screamed as Sheldon procured the emergency flashlight from the nightstand. He continued where he left off. "Or we could give my way a go, how about that?"

She nodded again and he wrapped his long arms around her tiny body. "Okay," he smiled. "Here's what's really going on up there. We'll start with lightning. Lightning is an electric current. It strikes when frozen raindrops in a thundercloud bump into each other and create an electric charge."

"Oh," Mia interrupted, already feeling better.

"Hey, I'm not done yet, Missy," he laughed, tickling her stomach. She giggled as he resumed his lesson. "The negative charges at the bottom of the cloud eventually seek out the positive charges on the ground. When they connect... Zap!" he yelled, pressing his finger to the tip of her nose. "Lightning strikes!"

She giggled again as he pressed his lips to the side of her face, gobbling at her rosy cheek.

"Now thunder," he continued, "is the sound of lightning. When a lightning bolt travels to the ground, it leaves a little hole in the air called a channel. Thunder is just the sound of the air collapsing back into the channel."

"Okay," she said, her eyelids starting to droop.

"Now that's not so scary, is it?" he said, slipping out from under the bedding.

"No," she responded sleepily, shaking her head.

"Good," he said, tucking her in like he'd done hours before. "The next time you hear thunder, just remember that it's only air, okay?"

"Okay."

Just as he leaned down to place a kiss on her forehead, a soaking wet Amy rounded the corner. "Ooh, looks like I found the party," she commented, nearing the father and daughter.

"Hi, mommy," said Mia.

"Hi, mommy," Sheldon echoed, joining her at the foot of the bed.

"Daddy taught me a new story about thunder and lightning," she said, yawning.

Amy looked up at Sheldon. "He did?" Amy asked, a twinge of surprise in her voice.

"Yeah," the little girl said, cuddling her stuffed monkey. A peal of thunder broke the silence. "Don't worry!" she shouted from beneath the covers. "It's just air filling the channel."

Amy grinned. "Goodnight, Mia."

"Goodnight, Mia," Sheldon repeated, closing the door behind them.

Amy smiled at him.

"What?" he asked.

"You taught our four-year-old daughter a science lesson at eleven at night?" she laughed.

He wrapped his arm around her waist as they walked to their own bedroom. "It's always a good time to acquire new knowledge, Amy."