Naturalistic data from two Malay speaking children was collected in Singapore. The children were between 2 years 11 months to 3 years 5 months. Data was collected by using a video recorder and an external lapel microphone, which was pinned to the child.

The study was carried out primarily to collect spontaneous data on how children acquire WH questions. A number of story books, with some of titles already familiar to the child, were presented to try and elicit responses and queries from the child. The mother and the experimenter would tell the story and the child would then be given the opportunity to ask questions.

To complement the naturalistic data, a series of controlled experiments using Elicited Imitation and Pictured-Story Comprehension test were carried out as an additional measure to test (an older group of) children's knowledge of WH questions.

It was found that in spontaneous production, children between 2;11 and 3;5 ask mainly 'verbless' WH questions. In the experimental studies, children around 4 years old were found to be able to produce and comprehend both simple and complex (in situ and moved) WH questions with overt verbs.