I made this 100 square with the one more, one less and 10 more, 10 less window to help with counting up and down a number square. It also helps with becoming familiar with counting in 10s and recognising place value. Children love this tactile product especially with the windows they pull back to check they are right!
I cut the windows out then laminated them (then cut out again!) to ensure durability of the product.
This is my first resource that I am uploading to TPT so am really excited to get feedback from you. Enjoy!