Dinner is two different versions of cooked deer-thing, with yet more tubers and nuts and fruit. (Tetsuma's planning on looking for herbs and other plants next food sweep. At least something to make tea with.) 

"How've you been doing?" she asks.

"I'm not sure! I might be getting somewhere! But it might be my imagination and I don't know yet how to tell. How about you?"

"I've got the basics down - I know the first seal, and that it'll take more than one, a bit unusually for clone jutsu... Hopefully this won't turn into one of those ridiculous jutsu with four dozen signs."

"Four dozen, that sounds fun."

"I know! The whirlpool jutsu is like that - it uses a lot of chakra but still needs to be controlled pretty finely. I don't actually know how to do it, it's just always brought up as an example. People who are really good can get it down to fewer signs, though."

"Oh there's variance?"

"Yeah, both in terms of complete jutsu - there's variants between clans, especially between larger regions - and what people actually use. I've never actually heard of anyone not needing hand signs for ninjutsu outside of myths, but if you've got ludicrously good chakra control, and if you've practiced a jutsu a lot, you can reduce the number of signs needed."

"So what do the handsigns actually do, mechanically, to the jutsu, and why?"

"Control, mostly. It's really hard to shape chakra to do anything other than basic enhancement. Since people channel chakra through their hands, something about the way the hand signs shape the pathways helps shape the chakra. It's also a muscle memory thing - if you always shape chakra a certain way when you perform certain sequences, that reduces the amount of conscious control you need to put in." Then more details on the twelve basic hand signs. "There's also some rarer seals, like the clone seal - " which she demonstrates - "that're limited to a few techniques." Tetsuma doesn't know the theory for why each sign does its thing, though. There's definitely differences - clones made with Tiger versus Horse versus the clone seal act differently for instance - but again not sure why.

...huh. Can a given string of seals be used for more than one jutsu?

Yup! Especially short strings. 

Huh. Makes sense, with so few signs. Actually, why are there so few signs? Why not use other body parts, or the whole body as a sign?

There's actually a lot, the basic twelve plus the clone seal are just the widely used ones. Plus maybe it's really hard to figure out new ones? And there's not a ton of continuity or sharing among shinobi, if someone figures out an innovation it'll usually die with them or at most pass to an apprentice, maybe to their clan. 

As for 'why just hands' - it'd be difficult to do a full-body sign in the middle of a fight or while running, is Tetsuma's first guess. Fingers also have a lot more flexibility, and it's difficult to channel chakra through anywhere not hands or feet, which presumably signs involving something other than hands would require. She's not sure, though.

Well, they can experiment, after he's gotten good enough to actually be able to do things.

Sounds fun!

But now: food.

Food! Tetsuma eats a lot.

...Dayo does not eat that much. Dayo is kinda fascinated by this.

She finishes another piece of fruit, then grins. "Yeah, chakra use is really energy intensive. Normally I wouldn't need as much, but - " she gestures to the pile of failed experiments turned firewood. 

He giggles. "Yeah, sounds plausible."

"It's a lot like exercise, really."

"I don't eat that much when I exercise!"

She shrugs. "Well, I don't eat this much just for plain exercise, either."

Giggle.

And so over the next however long, Tetsuma settles into a routine. She finds more plants, hunts some (with varying levels of success), and after a few days finishes the wood clone. She starts on trying to improve the shelter jutsu.

Once Dayo figures out chakra manipulation, she'll teach him the very basics: how to channel chakra to your legs, to start with, to run faster and jump farther. How to reinforce your joints, so you don't injure yourself on landing. How to mold chakra with each hand sign. How to throw off genjutsu - Tetsuma turns Dayo's entire field of vision blue for practice.

Then, the simplest jutsu: the basic clone (insubstantial, doesn't cast shadows, but is a decent distraction) and the replacement technique (again, good for misdirection). Once Dayo's got the replacement technique down, they'll move to the body flicker, which requires insanely fast reaction times to be useful tactically for anything other than retreating. Then how to throw knives and shuriken, followed by the shadow shuriken jutsu. (Tetsuma starts on a jutsu to make wooden but usable bladed weapons.) 

Tetsuma's not certain how to test for elemental chakra natures, so Dayo can learn one basic jutsu for each of the five types (starting a campfire, pulling pure water from something wet, making a small breeze, generating a mild shock, and softening earth), to see which he has the least trouble with. Once they know his type, they can move on to more advanced techniques.