Grammar check for 7-year-old: 'The yellow school bus is full of kids on their way to learn'

Corrected sentence: The yellow school bus is full of kids on their way to school to learn.

Short alternative (even simpler): The yellow school bus is full of kids on their way to school.

Step-by-step explanation for a 7-year-old:

1. Capitalization: The sentence starts with a capital letter, which is correct.
2. Subject and verb: "The yellow school bus" (the subject) and "is full" (the verb) match and are correct.
3. Clear meaning: "on their way to learn" is understandable, but we usually say where they are going. Saying "on their way to school to learn" or simply "on their way to school" makes the sentence clearer.
4. Punctuation: No extra punctuation is needed; the sentence ends correctly with a period.

So your sentence was almost perfect — changing "on their way to learn" to "on their way to school to learn" or "on their way to school" makes it clearer.