Here is a clear, corrected version and a simple explanation for an 8-year-old.
Corrected sentences:
In winter, the Arctic fox is white. In summer, it turns brown. The fox molts (this is called moulting) when its fur changes.
Why these changes help:
- We put a period between the winter and summer parts to make two short, easy sentences: that is clearer for young readers.
- We keep the comma after introductory phrases like "In winter," and "In summer," because that is the usual grammar rule.
- Instead of saying "goes through moulting," we use the simple verb "molts" so the sentence is shorter and easier to understand. (You can also say "goes through moulting," but "molts" is more natural.)
- Note: "molts" is the American spelling. In British English you can spell it "moults" or say "moulting." Both mean the same thing.
What "molting" means:
Molting means the fox loses its old fur and grows new fur. This helps the fox stay warm in winter (white fur blends with snow) and hide better in summer (brown fur blends with rocks and plants).
If you want, I can rewrite the sentences in different ways (shorter, more detailed, or with pictures) so they are perfect for an 8-year-old reader.