“Some grammatical morphemes tend to be acquired early, some late — and instruction does not change this order.” –Dr. Stephen Krashen

Krashen and his collaborators (including Dulay & Burt, 1973, 1974) studied child ESL learners and proposed the following general sequence for English morphemes:

Key points about NOH

1. Acquisition ≠ learning

   • NOH predicts what learners acquire naturally, not necessarily what they are explicitly taught.

2. Order is relatively stable across learners

   • The same sequence is observed in children and adult ESL learners.

   • L1 background has surprisingly little effect on the order.

3. Instruction has limited effect on order

   • You can teach a structure early, but learners may still acquire it later if it’s “later” in the natural order.

4. Focus on meaning and input

   • Krashen emphasizes comprehensible input (n+1) rather than explicit grammar drills.

Mnemonic Order

“ING PLU PREP POS COP AUX ART PAST 3PS IRR”

• ING = progressive

  • He is running fast.
  • They are singing loudly.
  • I was reading a book.

• PLU = plural

  • I have two dogs.
  • She bought three apples.
  • The cars are parked outside.

• PREP = in/on

  • The book is in the bag.
  • She is sitting on the chair.
  • Put the pen in the drawer.

• POS = possessive

  • That is John’s hat.
  • I like my sister’s room.
  • The dog’s tail is wagging.

• COP = copula be

  • She is happy.
  • They are tired.
  • I am ready.

• AUX = auxiliary be

  • He is running.
  • They were sleeping.
  • I am studying English.

• ART = articles a/the

  • I saw a cat.
  • The dog is barking.
  • She wants a sandwich.

• PAST = regular past -ed

  • I walked to school.
  • She played the piano.
  • They cleaned their room.

• 3PS = third-person singular -s

  • She runs every morning.
  • He likes ice cream.
  • The dog barks loudly.

• IRR = irregular past tense

  • I went to the store.
  • She ate lunch.
  • They saw a movie.