Discipline means teaching, not punishing. For toddlers — whose prefrontal cortex, the seat of impulse control and reason, is still in early development — effective discipline strategies work with the brain's architecture rather than demanding capacities the brain doesn't yet have.
Natural and logical consequences are more effective than arbitrary punishments. A natural consequence follows directly from the behaviour (running on wet concrete leads to a fall); a logical consequence is related and proportional (throwing food ends the meal). Both teach cause and effect in ways that are comprehensible to a toddler.
Time-outs are among the most overused and least effective toddler discipline strategies. They send children to isolation when they are least regulated and least able to reflect — and offer no teaching about what to do instead. Brief, calm 'time-aways' — where the child is removed from a situation and briefly reconnected with the caregiver — are more useful.
Positive reinforcement of desired behaviour is more powerful than attention to undesired behaviour. Catching children being good — and being specific about what you noticed — builds the target behaviour more efficiently than most consequence-based approaches.
The most important element of any discipline approach is connection. Children who feel securely connected to their caregivers are more motivated to cooperate, more open to guidance, and more resilient in the face of correction.
Consistency between home and daycare is essential. Children who experience dramatically different expectations in different settings often test both — not out of defiance, but out of a genuine need to understand the rules of each world.