For my 2nd grader I posted 2 hundred charts. On one I colored the 5s and 10s, on the other the 2s. It has helped her a lot as she learns to count them from memory.
Maps definitely important. And a globe. I also have posted the manuscript and cursive letters for my 2nd and 3rd graders as they learn to make the letters correctly. I also will be posting some Scripture and wise sayings from time to time, especially while my 3rd grader delves more into personal development and her subjects get more difficult.
My oldest will be 9 in a month, so I can’t help you with the older kid visuals. Hopefully someone else will chime in. 🙂