Develop a research question in developmental psychology.
Create 3 separate designs: a longitudinal, cross-sectional, and sequential research design to examine that topic.
You choose (when applicable, depending on design type):
The time length in years you want the study to be conducted for.
How often the observations would occur.
The number of age groups.
Which age(s) are included in each age group.
Make sure you give a rationale for all your decisions.