Let's look at your sentence and make it a little clearer and grammatically correct step by step:
Original sentence: "Baby water birds often start out with fuzzy feathers that can easily get wet. So many water birds, like swans, taxi their chicks around on their backs till they are ready to swim."
Here's a corrected and improved version:
"Baby water birds often start with fuzzy feathers that can easily get wet. So, many water birds, like swans, carry their chicks on their backs until they are ready to swim."
Explanation:
- Changed "start out with" to "start with" to sound more natural and simple.
- Added a comma after "So" to separate the clauses properly.
- Replaced "taxi their chicks around" with "carry their chicks" because "taxi" is a bit complicated for an 8-year-old and might be confusing.
- Changed "till" to "until"; both are correct, but "until" is a bit more formal and clear.
This way, your sentence is correct and easy to understand!