lunch – n. a light meal eaten in the middle of the day

guitar – n, a musical instrument that is held against the front of your body and that has usually six strings which are played with your fingers or with a pick

Here are some practice clauses for you to connect with "when" or "while:"

1.The cat is sitting on the table / I am writing a letter
2.I woke up / The dog barked loudly
3.A rainbow appeared / I was looking out the window