I found that when I was teaching the unit on atoms, I got really tired of drawing so many plus and minus signs, and it took a while for me to draw out a bohr model on the board. So I made these simple subatomic particles, printed them on different colors of paper, cut and laminated them, and put magnets on the back. Voila! Now I can quickly and easily construct a bohr model on my board for the students to see. They're bright and colorful and the students like to use them too!