If you have camping gear, spend an afternoon setting up a campsite, teaching them to set up the tent, hang a bear bag, where to cook, + Leave No Trace principles
Tell them to hide something and create a treasure map for you to find it. Block off 30 min. so you can go on the treasure hunt. Entertained my kid for an hour.
Read a book and write down new words. Then make the words out of playdough.
Go on an alphabet hunt around your home or yard. Make a list of the alphabet letters and have kids cross out the letters you find or objects you find that begin with each letter.