Monitor Kid using computer, just let kid using some limited programs, close other browsers. If the kid switch window, then make sound to alerm. Works for Windows system.

Kid_Monitor.py

# To run this program in backgorund, run it on command line: pythonw Kid_Monitor.py
# SoundVolumeView.exe is a simple tool for Windows that adjust system volume level.
# Can be downloaded from https://www.nirsoft.net/utils/sound_volume_view.html.
import win32gui
import time
import winsound
import os

i = 0
while i<=1:
    # Loop every 3 seconds.
    time.sleep(3)
    # Prevent kid mute or adjust sound volume.
    os.popen('SoundVolumeView.exe /SetVolume {0.0.0.00000000}.{e8953996-74fd-430d-ba38-6a272650d013} 20')
    os.popen('SoundVolumeView.exe /Unmute {0.0.0.00000000}.{e8953996-74fd-430d-ba38-6a272650d013}')
    
    # Kill other browser windows.
    os.popen("taskkill /f /im opera.exe")
    # os.popen("taskkill /f /im chrome.exe")
    os.popen("taskkill /f /im firefox.exe")
    
    # Check the current window title, if not correct, make sound alerm.
    w=win32gui
    title=w.GetWindowText(w.GetForegroundWindow())
    tile = str(title)
    print(title)
    if not (title.find('ClassIn')>=0 or title.find('思维')>=0 or title.find('数学')>=0 or title.find('哔哩哔哩')>=0 or title.find('红星')>=0):
        winsound.Beep(400, 700)