Teacher's Pet

A student who is the teacher's favorite

Step by Step

Gradually, one stage at a time

Strike While the Iron Is Hot

To act at the right moment when circumstances are favorable

Cry over Spilt Milk

To be upset about something that has already happened and cannot be changed

Sky Is the Limit

There is no upper limit to what can be achieved

Eye Candy

Something or someone that is attractive to look at but not necessarily substantial