Let's look at the sentence: The brain is squishy like jelly, but the bony skull keeps it safe.
This sentence is grammatically correct for a 6-year-old! Here's why:
- Subject and verb: The brain is (correct verb for the subject).
- Adjective 'squishy': accurately describes the brain.
- Use of 'like' to compare the brain to jelly is clear and simple.
- Comma placement: The comma before 'but' connects two ideas nicely.
- Pronoun 'it': correctly refers back to 'the brain.'
- Verb 'keeps': agrees with singular subject 'the bony skull.'
So your sentence is good just as it is! Well done!