Dicot stems have a circular arrangement of vascular tissues, whereas the stems of monocots have vascular-tissue bundles scattered throughout. In monocots the vascular bundles also tend to be toward the outside of the stem. Dicot vascular tissue forms a cylinder near the center of the stem. Monocot roots, interestingly, have their vascular bundles arranged in a ring. Dicot roots have their xylem in the center of the root and phloem outside the xylem. A carrot is an example of a dicot root.
This video explains how to prepare temporary stained glycerine mounts of transverse sections of the stem and root of Dicot and Monocot plants.