Rollover is an advanced exercise but the warm-ups either one-leg roll-over prep or roll-over prep can be done instead.
With either of these two exercises you can further warm-up or prepare by doing front/back to help your students to find neutral pelvis and then have them place the heels of their hands at the top of their thighs and with the pelvis in neutral position on an inhale (as this prepares for roll-over breathing) you press the thighs away with your hands and flatten the lower abdomen or engage ‘the powerhouse’ and relax on the exhale.
By doing this you train the body to keep the pelvis in neutral position rather than tilting forwards into an anterior tilt as the thighs move forward in space away from the body on an inhalation.
This cueing encourages students to engage the transversus abdominus and the multifidus (‘the powerhouse’ muscles) to active core strength for stability while at the same time doing an inhalation which is opposite to what the body naturally wants to do and so require concentration and practice.
Then, as you do either of the two prep options (start with one-leg roll-over prep and then do roll-over prep either in the same class progressively on do one-leg on class and two-leg the following after which you could introduce the roll-over with just a slight pelvic lift and then a full and then the roll-over and students can stick with what they are able to do either the prep, slight lift or full exercise) and encourage the same awareness and muscle activation as the extended legs go away from the body on the inhale.
This way you gradually build up the ability, strength and muscle co-ordination to properly and safely execute the roll-up.