import tkinter as tk
from threading import Thread
from time import sleep

def print_slowly(string):
    words = string.split()
    for word in words:
        sleep(1)
        print(word)

class App(tk.Tk):

    def __init__(self):
        super().__init__()
        self.text = tk.StringVar()
        tk.Entry(self, textvariable=self.text).pack()
        tk.Button(self, text="Run unthreaded",
                  command=self.print_unthreaded).pack()
        tk.Button(self, text="Run threaded",
                  command=self.print_threaded).pack()

    def print_unthreaded(self):
        print_slowly(self.text.get())

    def print_threaded(self):
        thread = Thread(target=print_slowly, args=(self.text.get(),))
        thread.start()

App().mainloop()