Koch Lesson 3: Add the Letter S

Why this step

S is three short elements — the bookend of SOS. In Koch it arrives after you already copy two dah letters and R. The job is to hear a burst of dits as one letter, not as “E E E.”

What to hear

S is a compact “dit-dit-dit.” M is “dah-dah.” They are opposites in duration and tone. If S smears into a single buzz, your audio is too fast relative to your attention; keep WPM, take a shorter session.

Drill

Active set: K, M, R, S. Copy SK as two letters when you are ready, but the module still quizzes one character at a time. Share the lesson-3 practice URL so someone else uses this exact set.

Letter groups you can type in the translator once the ear is warm: S, SK, RS, MS

Pitfall

People who learned SOS visually send S as three slow taps. Koch wants the three dits inside one letter-length at 20 WPM.

Practice text

Contrast S against M: SMS MSM. Then four-letter sets SKRM. Count dits only after the tone stops — three equal short elements = S.

Common mistakes

• Splitting S into three separate E letters at slow speed.
• Confusing burst of dits with future letter I (two dits) — I is not in this set yet.

Session notes

Three dits at speed feel like a texture change in the audio band. If your speaker rolls off treble, short dits blur — try headphones or a different device before lowering WPM. Practice S against M in the same minute so your ear contrasts burst-length against dah-length. Avoid saying “three eees” aloud; that reintroduces alphabet thinking. When copying groups like SK or RS, write the letter only after the full group ends. If accuracy stalls below eighty percent for two sessions, repeat lesson 2 drills for ten minutes, then return — do not add U early.

Practice schedule

Days 1–2: S against M so short bursts and dashes stay distinct. Days 3–4: four-letter sets from this lesson only. Days 5–6: headphones if the speaker smears dits. Day 7: a short mixed run. If accuracy drops, repeat lesson 2 for ten minutes the next day.

SOS as a prosign uses three letters; lesson 3 grades isolated S only.