Please help me understand variable scope in Ruby

scope.rb

puts "Please enter num1"
num1 = 13
puts "At the beginning I am:  #{num1}" #num1 = 13

def change(num)
  num1 = num
  puts "Inside of the change method I am: #{num1} " #num1 = 47 because num1 is local inside change
end

change 47

puts "But outside of the change method I am still: #{num1}" #num1 = 13 because change did nothing to the original num1

array  = ["crazy example"]

array.each do |e|
  num1 = e
end

puts "But look now, I've completely changed num1 to: #{num1}" #num1 = crazy example because it was changed in array.each