Sometimes I open up the discussion to the entire class. These impromptu reminders help keep students on track. I set up a system for storing materials and familiarize students with it. It's important for students to know where and how to store materials. A clear system makes the materials more accessible.
Some teachers designate and label space on bookshelves.
Others use zip-top plastic bags and portion materials into quantities useful for pairs or groups. Still others place a supply of each material at students' tables so they're always within reach. Time for free exploration is worth the investment. Whenever I introduce a new material, I allot at least one math period for this. Teacher demonstrations alone are like eating a papaya in front of the class and expecting children to know how it tastes.