Step 1: Recall the idea:
Learning any language means learning to take in and to give out messages.
Two skills help us take in a message and two help us give it out.
Step 2: Name the four skills:
1. Listening: understanding what other people say.
2. Speaking: saying our own ideas aloud.
3. Reading: understanding written words.
4. Writing: putting our ideas on paper or screen.
Step 3: Group them:
Listening and reading are receptive skills, because we receive the message.
Speaking and writing are productive skills, because we produce the message.
Final Answer:
The four key language skills are listening, speaking, reading and writing (LSRW).