What's wrong with my disappearing platform script?

I'm attempting to code a disappearing platform with multiple parts. Once the player steps on the platform, the entire thing should gradually disappear and reappear shortly after. The script is also meant to apply to every model in workspace by the name of "Platform". (no quotes)

Once a platform is stepped on, no errors are shown yet nothing happens.

Here is my script:

num = 40

local platform = Instance.new("Platform",game.Workspace)

for _, instance pairs(workspace:GetChildren()) do
	if instance.Name == 'Platform' then
		for _, instance_2 in pairs(instance:GetDescendants()) do
			function onTouched(hit)
				for i = 1, num do
				instance.Transparency = 0.5+1/num/2 
					instance.CanCollide = false
					wait()
				end
				
				for i = 1, num do
				instance.Transparency = 1 - i/num/2
					instance.CanCollide = true
					wait()
			end

			instance.Touched:connect(onTouched)
		end
	end
end

Also I have extremely little knowledge of Lua, so you may have to explain this to me in caveman terms.