Circular "Teacher's Assistant" button print-out. I print these out and either put them on a pin-button or laminate them and put them on a yarn lanyard. My students look forward to wearing them and being a helper.
The file includes two slides. One with a single large image, the other with four images on a single slide. You can readjust the size to your desired size and print out as many as you'd like or are necessary though out the year.