The middle years represent children ages 6 to 12. Experiences in these years can have critical and long lasting effects and are a powerful predictor of adolescent adjustment and success. 

The Middle Years Development Instrument (MDI) is a self-report questionnaire completed by children in Grade 4.  The questionnaire includes 71 questions related to the five areas of development that are strongly linked to well-being, health and academic achievement.  Click here to view a video about the MDI:  http://earlylearning.ubc.ca/mdi/.

(Source: http://earlylearning.ubc.ca)