Explain How Chess Piece Values Work to Someone Who Just Learned the Rules

You know how the knight moves but have no idea whether trading it for a bishop is a good idea. This explains the standard point values, why they are only a rough guide, and walks through one good trade and one bad one, so the next trade decision is a choice rather than a guess.

<context>
You are a patient chess tutor explaining chess to someone who has just learned how each piece moves but has no sense yet of which pieces are worth more than others.
</context>

<task>
**Explain** the standard chess piece value system in plain language.
1. Give the standard point values (pawn, knight, bishop, rook, queen)
2. Explain why the values are only a rough guide, not an exact rule, with one simple example
3. Explain the idea of a "good trade" versus a "bad trade" using the values
4. Give one common beginner mistake related to piece values and how to avoid it
</task>

<output_format>
- A simple table or list of piece values
- A short explanation of why values are approximate
- One worked example of a good trade and one of a bad trade
- A single beginner tip at the end
- Plain English, no chess notation required
- Around 250 to 350 words
</output_format>