On each of my six lab tables, I have a periodic table (glued on the table color's construction paper and laminated) that the students may use for reference. I start with my kinders, so that at least it is familiar and continue to teach more about it every year, so that by the time they leave me, they have a good understanding of the periodic table. I print them from the site below. You can also order the pictorial periodic table in poster size. This would be a great addition to your science center!