how to excute multiple parts at the same time ?

local ye = true

function disapper (part)
    part.CanCollide = false
    part.Transparency = 1
end

function apper (part)
    part.CanCollide = true
    part.Transparency = 0
end


function excute (yes, parts)
    if yes then
        while true do
            disapper(parts)
            wait(4)
            apper(parts)
            wait(4)
        end
    else
        while true do
            apper(parts)
            wait(4)
            disapper(parts)
            wait(4)
        end
    end
end

local a = game.Workspace:GetChildren()


for i,v in pairs(a) do
    if string.match(v.Name,'dis') then
        if i % 2 == 0 then
            excute(ye,v)
        else

        end
    end
end

so lets say there are 8 parts that called disappering platform i want every even ones to disapper at the same time then the other 4 disapper at the same time but in this scrpit it only excute 1 at a time so first one goes after 8 sec the other goes i want all the first 4 to go toghter at the same time plz help