There are a number of effective ways to make sure that you are involving all your students fairly and consistently in class discussions, responses, and activities. 

1. For each class create a set of popsicle sticks with each student's name on a stick. Color code the sticks for each class set by swiping some color at one end. Keep the sticks in individual cups and then when you want to call on someone to answer or respond, draw a stick from the cup. If the student you called on can't answer or wishes to pass, put the stick back in the cup. If the student responds appropriately, set the stick aside until all sticks have been used or the class ends. At the end of class it is easy to track which students you need to give credit to for responding. You can start fresh each day or bundle the responders sticks with a rubber band and start with students who have not had a chance to respond. 

2. When students enter the room, give each of them a number on a file card. Randomly mix the cards. When you want a response, call out a number and that person can write the answer on the back of the file card, initial it and then read it aloud to the class. Then he/she can call out the next number for a responder and so on. Collect the cards at the end of class and again you will have a painless way of keeping track of who is involved and who is not. 

3. For small group responses: as students enter a classroom hand each one a colored piece of construction paper (2x2 inch square for example) and have students sit in groups by color of paper. When you need an answer or response, call on group by color : Green group, for example. Give them a few seconds to discuss their answer and then report to the class. This is a variation on the "numbered heads together" cooperative learning tech.Another way to organize groups is to hand each student a playing card - hearts, club, spades, diamonds, and have them sit together will others of the same "suit." Then you can call on members of each group based on the value of their card. Kings would go first, queens second, and so on down to the lowest card of the suit in the group. 

If you have additional ideas to share, email me and I'll post them.