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Grace pulled on his swim shorts and shirt, fumbling a little awkwardly with the ties but getting it eventually. He’d started to develop arthritis in his hands- it was not fun. The Eridians were trying to figure out a solution, but the human body wasn’t exactly easy to study, even for beings with perfect memory.
He grabbed his forearm crutches and made his way to the kitchen, a hot cup of coffee already waiting for him. Armando had been expanded from just the one set of arms to a bunch of different, smaller robots all around the house, performing different activities. The cutest was the one in his pantry. It was just so small and yet so determined to get things from the high shelves!
The nutrient shakes did not taste as bad as they used to, partially because he’d gotten used to the taste, and partly because they’d added a shit ton of sugar to the mix. His mornings were spent alternating drinking a shake and fake-coffee, looking out at the beautiful biodome as the waves rolled in.
Today was the annual field trip for his students. It always happened 3/4ths of the way through the school year, in the vehicles he’d nicknamed Erid Rovers after seeing them carrying his students during their first field trip. They really did look a lot like a mars rover, especially with the six wheels and large, rectangular body. However, they were much taller, with seats all along the inside for the children to sit. It was just too dangerous to make suits for all the children, especially with the water, so they’d found a solution in adult-driven ‘field trip buses’ to bring his whole class inside. Of course, some parents still did not allow their children to enter the ‘flammable atmosphere.’
He felt bad for those kids. Getting left out of field trips sucked, even if he knew that realistically this type of field trip was significantly more dangerous than any he’d led back on earth, even with the statistics regarding car crashes.
Like clockwork, Rocky appeared at his door, knocking like the british were coming. He chuckled and walked to the door, the crutches doing wonders for his shitty joints. He wasn’t using his wheelchair today, he didn’t like to get the cushioning wet, even if it was (mostly) waterproof.
“Grace ready for students?!” Rocky chirped, clearly very excited. They also got to teach as well, showing the kids the mechanisms that kept Grace alive in his little bubble. Of course, Rocky also was there to be his lifeguard, because they got incredibly anxious about swimming. Eridians were significantly denser than water and could not simply stop breathing like humans did, so any interaction with the ocean was basically a death sentence. And Rocky was the only one crazy enough to actually like frolicking in the waves, other than the ocean explorers, who were too busy researching the ocean to supervise one old man.
“I’m so ready,” Grace said, “Are they getting into the buses now?” He followed Rocky down the newly-installed ramp to the beach (after a fall in his crutches and a sprained ankle, the stairs had been permanently retired).
“Yes, yes, yes. We start with biodome mechanisms, then move on to swimming,” Rocky said firmly, with no room for argument.
“Of course,” Grace agreed, “I’ll follow your lead.”
The airlock opened with a quiet whirr. Then, three buses full of Eridian children, with two adults per bus, drove in, the sounds of awe clear even from halfway across the beach. Grace waved and watched a bunch of claws wave back. It was clear that the students were a little overwhelmed by the waves and the wind and… well, everything about the biodome, but he could sense that they were eager to learn.
“Welcome to my home!” Grace exclaimed as the buses pulled to a stop in their first area. The routes were carefully planned to avoid any dangerous areas while also showing as much of the biodome as possible.
Rocky and Grace talked for a while there. Grace eventually ended up sitting on top of Rocky when his joints began to protest the stillness. Rocky muttered complaints, thankfully omitting his usual swearing in front of the children.
They explained the composition of the atmosphere, the sand and the stone, the parts of Earth the biodome was based on, and all the problems they had to solve to even get a place like this to exist.
The buses moved to a spot where the Biodome Control Center was just visible (audible?) on the other side of the xenonite. If Grace squinted, he could see some of the many, many Eridian workers there waving back as the children trilled at them excitedly.
Rocky pointed out the different control rooms. The ocean control center, the house control center, the illumination team, the atmosphere team, the medical team, and the food team. All of the kids made ‘ewwww’ noises at that. Some things were the same between planets, Grace thought with a grin.
“Alright, you guys have to promise not to get super grossed out when I say this,” Grace said, “But on Earth, since humans have to eat so often, this would usually be around the time that Earth children would take a break and have lunch. Luckily, we don’t have to do that today!” Some of the students groaned at the mention of eating, but Grace pushed on. “Let’s go down to the shore. We’re going to talk about buoyancy!”
The rovers rumbled down the hill, all of the Eridian children chittering excitedly. They’d heard that Grace and most humans could naturally float on water, but even if all of the math proved it, Grace already knew that they would still react with shock, just as Rocky had when the biodome team had finally gotten the temperature right and he’d been able to swim.
Grace sat on a flat rock right in front of the water as the rovers pulled into a circle around him. The nice part about echolocation was that he had to worry way less about line of sight and just focus on talking loud enough that everyone could hear him. He removed his shoes and socks as he spoke.
“So, last class, we all did the math on how exactly human bodies are composed. Now, I am a little on the fat side for a human after recovering from my starvation, so that means that I have about 30% body fat. Does anyone remember why fat is important when talking about swimming?”
A few claws shot up; he called on one of his youngest current students, a pebble named Sheila. “Fat is less dense than water, so it floats!” They trilled. Grace nodded.
“Yes, very good!” Grace praised, standing up a little unsteadily. Rocky was immediately there to hold him up. “Alright, now, since I am living in more gravity than I’m used to, that also means that my muscles have gotten bigger since I recovered from my malnutrition. Now, what is important about muscle when swimming?”
Grace called on Elijah, a pebble from a member of the biodome illumination team. “Muscle is more dense than water!” They said.
“Yes! So, since I have both muscle and fat in my body, what will determine if I sink or float? Well, there’s obviously a lot of factors, I know,” Grace said, still leaning on Rocky for support. Even though he knew that xenonite literally could not rust, some human instinct in him liked to keep all metallic things away from the water, so his crutches sat next to his shoes, socks, and the towel that he’d laid out the previous night. “But the main thing that will determine if I sink or float is the overall density of my body compared to the water. And since I have quite a bit of less-dense fat, I will naturally float! Plus the air in my lungs too.”
“Remember to explain how you do not drown before you jump in the water,” Rocky reminded, clearly thinking back to when Grace had ducked under with no warning and sent Rocky into a panic.
“Oh, of course. Now, class, I’m going to come closer to you. I want you to listen carefully to my lungs, and compare that with how Eridian breathing works.” He took a deep breath and held it, listening to dozens of little claws tapping at the glass barrier.
“Not breathing!” Someone shouted, followed by the children all yelling in alarm. Grace quickly took a breath and raised his hand, the students quieting down shortly after.
“Humans can choose whether or not to breathe. When we don’t breathe, no water can get into our lungs. That’s how humans can swim and dive under the water safely. Do you all understand? You’re not going to panic when I get in the water?” He asked, only a little worried. The demonstration of his breath-holding abilities had calmed down the previous classes during their field trips, so he knew that it would work with this group.
The students made their little trills of agreement and settled down to watch calmly. Leaning on Rocky, Grace made his way back to the shore. The water lapped at his toes, his body relaxing in anticipation.
“Since it will be a little hard to understand me while I’m in the waves, Rocky will teach you about all the things I’m doing in the water! Ready, class?” Grace waved and walked into the water, Rocky following only until Grace was deep enough that his aching joints protested a little less. They walked back up to the shore as Grace relaxed into the water, already floating on the surface. If he strained his ears, he could hear Rocky talking.
“Grace is floating now,” They said, “And that is amaze! Because humans evolved from aquatic species, their ancestors learned how to hold their breath to hunt in water when food on land is scarce. There are Earth animals that have same lungs as humans that went back into the water for more food, and can hold their breath for hours!”
Just barely, over the rush of the waves, Grace could hear the little ‘amazes’ from his students. He grinned and started backstroke swimming, careful to go slow so they could catch all his movements.
“Grace swim every day on Erid because human joints are fragile, and the gravity is unhelpful. In the water, the gravity is not a big deal. Does anyone know why?” Rocky asked. Aw, he was becoming such a good teacher. He used to absolutely suck at it (cough cough, learning to pilot). “Yes, Lee?”
“Because of the buoyancy! Less force of gravity, less pressure on joints! Body is supported by water!” Grace smiled at their enthusiasm, flipping over to freestyle swimming. He heard a couple quiet cries of alarm, but Rocky quickly diffused the panic.
“Humans have different styles of swimming. Called backstroke, freestyle, and breaststroke. Grace say there are more, but he does not know them,” Rocky explained, “And Lee is correct. The water supports the joints, so force of gravity does not pressure them. Is why Grace swim in ocean many many times, to keep healthy with less pain.”
The students hummed sadly, all knowing that Grace was in near-constant pain due to the extra force of gravity. Now that Rocky had mostly explained everything, it was time to pull out the big guns. He took a deep breath, treading water, then dove under, keeping his eyes closed to avoid the sting of the saltwater. He resurfaced only a few moments later, noting that some of his students still shouted in alarm when he went below the surface. To show that he was perfectly fine, he waved his hand in the air, watching as his students waved back.
After a few more minutes of swimming, Grace returned to the shore and answered any and all questions, joyfully and enthusiastically. He dried his legs off and put his shoes back on, walking with the buses to the airlock. Rocky stayed behind with him as his students left, all talking in excitement about what they had seen.
“That went well,” Grace said, leaning heavily on his crutches. His clothes were still damp, which was kind of annoying, but he could manage. He watched the airlock cycle and his students get out, all of them waving goodbye through the double-paned xenonite glass.
“Yes. We are good team of teacher, statement,” Rocky said.
“You only say that because I taught you how to teach without getting super impatient,” Grace teased, turning to go back to his house. Rocky chirped in irritation and followed, their loping gait a bit awkward in the sand.
“Whatever. Can watch movie now, question?” Rocky asked. Grace knew that they just wanted to spend time with him, so he nodded.
“After I take a shower, yeah,” Grace said. Rocky made an impatient sound but did not argue, knowing that nothing they would say could make Grace change his mind.
“Humans obsessed with water,” Rocky complained.
“Yep!” Grace said, popping the p.
“Done being wet so have to go get more wet.” Rocky stomped through the sand.
Grace smiled. “Pretty much.”
Rocky huffed. Grace laughed. Then, they both laughed together, and everything was alright.