Mind Matters Chapter 2: Toddler Development: 18 Months to 5 Years

11 min read

This series of articles has been adapted from [Mind Matters in Children] by Dr Kenneth Lyen. It delves into both the normal as well as the abnormal functioning of a child’s mind, and gives practical advice on how to manage children’s mental health and problems like ADHD, dyslexia, autism and depression.


Children between the ages of 18 months to 5 years  grow and develop remarkably quickly, and they become more independent. Sometimes they want to assert their authority by doing what they want to do and disobeying their caregivers. Thus, this can be a very challenging phase of their lives. Understanding their evolution at the different stages can be crucial in guiding them along the path leading them to achieve their fullest potential.

Toddler development is the continuous process of changes in physical, language, intellectual, behavioural, emotional and social functioning from 18 months to 5 years. 

Development does not follow a strict linear timeline, and some areas can progress at different rates. For example, some children’s physical development occur early, while others’ speech and language might advance even faster. Parents and caregivers should also keep a lookout for red flags where a toddler is unable to perform certain expected activities. It may be necessary to seek medical advice if these red flags crop up while observing the child.

18 Months Old

The 18-month-old child has been walking for a while but lacks coordination and often falls. They have started to climb stairs but may need a helping hand. They may also struggle to go down the stairs. They may be able to stack a tower of 3 to 4 blocks, use a spoon to feed themselves, and drink from a cup. They can use crayons to scribble on paper, and turn the pages of a book, often a few pages at a time. They can look at a story book while listening to it being read and point to pictures in the book. They may point to different parts of their body, to toy animals, and to do what they want. 

Often there is a broad social smile, and the 18-month-old can interact affectionately with their caregivers. Their vocabulary is rapidly expanding, and they can say 10 or more words, including the command “No!” while shaking their head. They might know the function of certain objects like the use of a spoon, a comb, or a toothbrush. They can imitate what adults are doing, such as pretending to wipe the table, and they can engage in pretend play, like feeding a doll. Some are able to take off their shoes but not put them on, and pull down their pants. 

They love to explore their surrounding environment, but they might prefer to have an adult around. Stranger anxiety may be more evident at this age, and they can become upset more easily, displaying noisy temper tantrums. When going to a new environment they can become clingier to their caregiver. 

Red Flags at 18 Months Old

  • Not able to walk
  • Not pointing to show things to others
  • Not knowing what familiar things (comb, spoon, crayons) are for
  • Not imitating other people’s gestures (clap, wave) 
  • Not able to say at least 6 words
  • Not learning new words
  • Not noticing or anxious when a caregiver leaves or returns
  • Losing previously learnt skills (saying words like “mama” “baba”)

2 Years Old

The 2-year-old can run very well and can climb up and down stairs, one step at a time. They can throw, kick, catch a ball, and climb onto furniture. They can build a tower of 6 cubes and turn picture book pages one at a time. They can remove shoes, socks, and underpants, but have difficulty putting clothes on. When asked to point to body parts like the nose or ears, they can do so. Their vocabulary is increased to over 50 words, and they can point to indicate their needs. Some can join two words together like “no more” or “don’t want!” Others can even use their own name to refer to themselves. They can understand simple commands like “give!”, or “fetch your shoes!” Defiant words like “No!” become more common, and they start to show wilful behaviour, leading to temper tantrums if they do not get what they want. 

The toddler can feed themselves with a spoon, but it can be quite messy. They can engage in make-believe play, such as pretending to cook. Socialising becomes more common but sharing of toys is inconsistent. Their sense of curiosity is enhanced, and they are beginning to explore their environment. Some children may try to take apart a toy to see how it works.

Red Flags at 2 Years Old

  • Not using 2-word phrases (“go away”, “don’t want”, “go out”)
  • Not knowing what to do with common objects (a toothbrush, mobile phone, fork)
  • Not able to imitate actions and words
  • Not able to follow simple instructions (“give”, “come here”)
  • Not able to walk steadily and confidently
  • Losing previously learnt skills (taking off shoes and pants, losing ability to talk)

3 Years Old

The 3-year-old is very energetic and likes to run and jump. Some can walk upstairs by themselves and stand on tiptoes. When given a tricycle, they may be able to pedal it. Generally, they can undress themselves by pulling off their shoes and pants, and they can assist in the removal of their vests. A few are able to dress themselves, and some can even do the buttons. 

They can be very expressive in their speech, with a vocabulary of about 200 words, and their sentences are at least 3 words long. By 3 years old, they can distinguish between “I”, “me”, “we”, “you”, and “mine”. Some like talking to themselves, while others are really quite noisy and ask a lot of questions like “what”, “where”, and “who”. They can carry on a conversation using sentences. A few have a short fuse, and they shout at or hound their caregivers until they get what they want. When taught, they can sing nursery rhymes, recite, and point to some alphabets. They can name the numbers 1 to 10 but may not appreciate the quantity they represent beyond 1-2-3.  

A 3-year-old toddler can sort objects according to their shape or colour, and build a tower of 9 blocks, and imitate building a simple bridge with just 3 blocks. They can copy a circle and a cross, and draw the head of a person with a couple of other facial parts. When given a crayon or paintbrush, some really enjoy their “art”. Given a pair of child-safe scissors, they are able to cut paper with it. Their imagination starts to flower at this age.

Red Flags at 3 Years Old

  • Falling down frequently when running, difficulty climbing stairs
  • Drooling frequently, or having very unclear speech
  • Unable to work out how to play with simple toys (shape sorters, simple puzzles, turning handle)
  • Unable to speak in sentences
  • Cannot understand simple instructions
  • Does not play pretend or make-believe activities
  • Does not want to play with other children or with toys
  • Does not make eye contact
  • Loses previously learnt skills 

4 Years Old

The vocabulary of a 4-year-old can reach 1,000 words or more, and their sentences can be over 4 words long. They can listen to and retell stories, they may recognise letters in their name, and even write their own name. Some appear to be able to read but more often they have just memorised the word prompted by visual cues on the page. They will know a few numbers, and some might even be able to add 1 + 1 = 2.

The 4-year-old can walk up and down stairs, climb ladders, run around on tiptoes, and hop on one leg. They can catch a bouncing ball and ride a tricycle. However, when asked to sit still, they may not be able to do so for more than a couple of minutes. Their fine motor skill is quite well developed, and they can thread beads to make a necklace, and hold a pencil quite firmly for drawing and writing. 

They are quite sociable and interact with their peers. Some are quite fast in learning about turn-taking and sharing. The toddler loves doing new things, and they can display a sense of humour, and engage in dramatic make-believe play. Singing nursery rhymes or reciting a poem from memory can often be heard. If their playmate or sibling are in distress, they will show concern. On occasion they can argue with others but using words rather than force. Their understanding continues to deepen, and they may know the difference between past, present, and future time.

Red Flags at 4 Years Old

  • Cannot jump in place
  • Problem scribbling using crayon
  • Not interested in interactive or make-believe activities
  • Ignores other children or doesn’t respond to people other than caregivers and family members
  • Refuses to dress, use toilet or sleep
  • Unable to retell a favourite story
  • Cannot follow 3-part commands
  • Does not understand the meaning of “same” and “different”
  • Reverses the use of “me” and “you” 
  • Speaks unclearly
  • Loses previously learnt skills 

5 Years Old

The 5-year-old is extraordinarily lively. They run, climb, swing, hop, skip, jump, and even dance to music. They can throw and catch balls, and pick up very small objects. They may be able to fully dress and undress themselves. Some are good at tidying up their room at home, but others may need prompting.

They are able to count 1 to 10, add 2 + 2 = 4, but may have difficulty with subtraction. They can copy a square and a triangle. They can also draw a person with 4 or more parts (head, trunk, legs, arms), sketch a simple house, and write several alphabets and perhaps even their own name. When colouring a picture, they can stay within the outline. At 5 years old, they may show a preference in using their right or left hand.

They usually love listening to stories being told and try to read kids story books. When asked, they can often retell or act out the stories they have heard. They enjoy hearing songs, jokes and riddles. Socialising with their peers plays an important part of their lives, and they like to make friends and participate in rowdy activities. They can understand many more words, including “because”. Some will feel a bit more mature and develop a sense of responsibility in looking after their friends and sibling.

Red Flags at 5 Years Old

  • Only shows a limited range of emotions
  • Swings in emotions  (from shyness and sadness, to extreme anger, temper tantrums, highly aggressive,
    and unusually fearful)
  • Displays prolonged periods of isolation, inactive, and withdrawn
  • Is easily distracted, cannot focus on one activity for more than 5 minutes
  • Does not respond to other people, or only responds perfunctorily
  • Cannot distinguish reality from make-believe
  • Can only play with a very limited games and activities
  • Unable to give their first and last name
  • Does not know how to use plurals or past tense properly
  • Does not talk about daily activities or experiences
  • Unable to draw pictures, just scribbles haphazardly
  • Cannot us a toothbrush, wash and dry hands, or get undressed without help
  • Loses previously learnt skills 

The 18-month-old to the 5-year-old period is an extremely important phase of a child’s development. Every opportunity must be taken to interact and educate them by talking and playing with them. Most paediatricians advise encouraging children to read paper books, write and draw on paper, and play with physical as opposed to virtual toys (real dolls, toy animals, Lego, Play-Doh, musical instruments, pretend cooking, building castles, etc). Physical activities like sports, dance, cycling, running, are all very important for the child’s development. Variety is the spice of life.

Over the centuries, toddlers and their families have had to face many difficulties. It is a battle that every age has to confront and overcome. The worry with the current Covid-19 pandemic is that children are exposed to the virus, which may have unforeseen consequences. We need to think of novel solutions to achieve our goals of raising children who are intelligent, creative, critical thinkers, kind, thoughtful, have total integrity, etc. Everybody has a role to play, including parents, relatives, friends, teachers, health professionals, and others. The results of parenting and teaching may not show up for decades. But it is a journey every family must take.


Children’s Bureau. Why the first 5 years of child development are so important.


Families For Life Parenting – Toddlers.

Families for Life Parenting – Young Children.

CDC’s Developmental milestones.

Written by Dr. Kenneth Lyen
Illustrations by Chua Jia Qi


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