Let's look at your sentences and make sure the grammar is correct.
Your sentences are:
- "Goose down makes an excellent filling for pillows and jackets."
- "A long time ago, people used big goose feathers to write."
Both sentences are mostly correct! However, there is a small improvement we can make in the second sentence to make it sound better. Instead of saying "big goose feathers," it might be better to say "large goose feathers" or simply "goose feathers," because people usually used the feathers called quills for writing.
Here's a corrected version:
- "Goose down makes an excellent filling for pillows and jackets." (This sentence is perfect!)
- "A long time ago, people used goose feathers to write." (Simplifying it is better.)
Or if you want to make it more interesting, you could say:
"A long time ago, people used special goose feathers called quills to write."
So your sentences are good, just a little change can help them sound better!