1. Virtuous Errors

2. Jean Berko Gleason and the Wug Test (1958)
What is the grammatical rule that the child has learnt when he / she answers ‘wugs’?

3. Adding endings to words
As they become older, children increasingly develop the ability to add endings (suffixes) or beginnings (prefixes) to words in order to express a different meaning. However, in doing so, they can make mistakes, and it is the mistakes that clearly indicate the rules which are being applied.
Eg. 1. The plural suffix ‘s’
Can you think of any other plurals in English which might cause confusion?
These are ‘virtuous errors’ - what is the technical term for the process which the child has undertaken?

4. E.g. 2. The past tense ending ‘–ed’
Can you think of any other verbs in English which might cause confusion?

5. Other affixes which are learnt by children: -er dis-
dis-
This is my sleeper…

6. Two more word-coining processes
Consider the following data from various children at different ages.
What processes have they undertaken in order to form the words they are using here? 
2 years: plate-egg (fried egg)
2 years: cup-egg (boiled egg)
3 years: rat-man (experimental psychologist)
3 years: rip-boy…. no, ripper (someone who rip things)
2 years 4 months: you have to scale it (weigh cheese)
3 years 11 months: I’m going to earth it (bury)
2 years 4 months: I’m souping (eating soup)
2 years 6 months: I’m darking the sky (colouring a picture)
3 years: How do you sharp this? (holding pencil)
 3 years: Full this up (holding out a cup)