After she helped the teacher, she had just enough time to make it to the beach without being late, she planned on having time to get Izuku, All Might, and herself some food before she came, but that plan was ruined after the tutoring.
When she got to the beach Izuku was running around carrying trash back and forth, from the sand to a truck. He didn't notice her form a few minutes so she just sat down and watched him, while also watching for All Might. After a few minutes passed, Izuku finally noticed her sitting in the sand.
"Oh, hi Big Sis."
"Hi, you aren't training too hard, are you?"
"No, it's fine."
"Where is All Might?"
"He went to get some food before you got here."
"Oh, Ok"
"So, should we start training?"
"Sure"
An hour passed of basic battle training, at least as basic as dragons consider it, it was quite advanced compared to human basic training.
All Might finally arrived with the food, and upon seeing his protegee being drilled in a fairly advanced fighting style by a complete stranger, he was quite confused.
"YOUNG MIDORIYA, WHAT IS GOING ON HERE?"
"Oh, this is my sister that I told you was going to help me learn some basic fighting techniques!"
"BASIC?! I THINK NOT, YOUNG MIDORIYA, THAT IS SOME ADVANCED STUFF THAT YOU ARE LEARNING!"
"It is?"
"I guess you can say it is rather advanced in normal terms."
"So, what you are saying is that this is hard stuff to learn, yet I am learning it this easily?"
"Yeah, pretty much."
"WE SHOULD EAT BEFORE THE FOOD GETS COLD!"
"That's a good idea All Might, let's go get that food, big sis!"
They were done eating the food in about 10 minutes because Izuku was very hungry after the intense training.
They continued Izuku's 'basic' battle training for another hour after they finished eating. After training ng was over for the day they went home.