Fortunately for me, Grace picked up on /r/ immediately! FYI: This does not happen often!! But when it does, pat yourself on the back for being such an amazing SLP.
I used to teach /r/ as the "smiling sound" but have since found that technique to do more harm than good. The kids were making really tensed-lip /r/ sounds that sounded extremely unnatural. What are some of your tricks?
Talk it up!