This will be explained later by antigen-antibody specificity. The figure below shows the relative position of wells to be cut in the agar plates with the straws. Toothpicks are good for removing the plugs from the wells. Extra plates and colored water can be used first for students to practice loading the wells. Remove plugs and label wells and plate.
Students select six different foods to load in the six outer wells.
Give students about 10 foods to choose from so there is variation in selections. Different pipettes should be used for each food and foods should not spill over edge of wells. Reagent A is placed in the center well. Plates can be stored overnight in a flat position at room temperature. Let students find precipitin lines.