Am I doing something wrong with this ModuleScript?

I am trying to experiment with ModuleScript's, I'm trying to make it print the name of every-thing in TestFolder but so far I am having problem's with this script. Can anyone tell me what I am doing wrong?

Server Script code:

script.Parent.MouseButton1Click:connect(function()
    local module = game.ReplicatedStorage.Modules.TestingModule
    module:GetChildren()
end)

ModuleScript code:

local module = {}

function module:GetChildren()
    for i,v in pairs(game.ReplicatedStorage.TestFolder:GetChildren()) do
        print(v.Name)
    end
end

return module

Output:

GetChildren is not a valid member of ModuleScript