Positive behaviour>Catch them being good

Here's some ideas of what you can look out for when practicing catching them

Make sure that you are genuine. Children can see through false compliments, exaggerations, and flattery. On the other hand, earning genuine praise makes children feel good.
After giving praise, make sure your children know exactly what they did that pleased you, so they can repeat the behaviour.
Be sure to tell them why you think what they did was good, and how it will benefit them and others.
Finally, get your child to respond to your praise so you know he or she understands why you are pleased with a particular action or behaviour.  

Behaviours to look for

coming into the classroom quickly and quietly
looking at the teacher quickly and quietly when asked to listen
following an instruction the first time they are asked
helping a classmate
being polite
tidying and cleaning up
working hard on a piece of work
putting their hand up and waiting to be asked to speak
holding the door open for someone
handing homework in on time
catching up with unfinished work or work missed due to absence
saying ‘please’ and ‘thank you’
asking for help when they need it
walking quietly around the school
listening well in assembly
providing a good idea or suggestion in a discussion
working well with a group of classmates
listening to another's point of view
telling the teacher of a problem in the playground rather than trying to sort it out by fighting
letting a teacher know if someone is bullying another pupil
carrying out a classroom job willingly and doing it well
looking after a younger pupil or a new pupil
offering help without being asked
taking turns; waiting for their turn
treating school books and equipment carefully
starting work quickly
keeping own books and possessions tidy
keeping own physical appearance tidy
moving from one task to another without teacher reminders
getting all equipment needed for a task without being told
telling the truth
listening quietly, looking at the speaker (‘paying attention’)
lining up quickly and quietly
being a good friend
willing to answer questions and make contributions to group discussions
remaining calm during a difficult situation
sharing equipment or activity with a classmate
taking a lot of care with . . . / putting a lot of thought into . . . a piece of work
finding something appropriate to do when they have finished their work early
speaking well in the school play or assembly
being willing to try something new or difficult
asking before they ‘borrow’ something
remembering to do something (eg taking a message home)
taking a visitor to their destination rather than just directing them
bringing appropriate books and equipment to the lesson

All these are an introduction to your specific comment about you think they have done