How did Ki-taek know that his son Ki-woo would decode the morse?

Question

In the movie Parasite, when Ki-taek ties up Geun-se in the basement, he struggles to get free and attempts passing morse code to Da-song, during which he says something similar on the lines of "at your age you should know these things" to Ki-taek.

Later in the movie, when the cops are looking for Ki-taek and he hides away in the basement of Mr.Park's house, he writes an entire letter to his son and passes the morse code every night, hoping that Ki-woo would find it one fine day. Did Ki-woo also know to decode morse like Da-song?

Answer 1

It's explained in the movie that both Ki-woo (poor son) and Da-song (rich son) were scouts so they understood Morse Code.

At the end of the movie, Ki-taek (poor father) says in that letter:

Perhaps you, if no one else, will be able to read this letter. You were a Boy Scout.

Earlier, Geun-se (basement guy) also mentions about Da-song:

Geun-se: Da-song will know it, since he's a Scout. Someone of your age should know it.

Ki-taek: Know what?

Geun-se: Morse Code.