Found this great article by Dr. Stephen Benham on the Alfred Music blog.
Here are the five best things you can do for your student:
To move more to music, especially music that has a steady pulse and clearly discernible rhythmic patterns.
To play a single string or single note, emphasizing connecting the internally perceived rhythm to the right-arm movements. (Suzuki did this very well with his beginning “Twinkle” variation patterns, but teachers often overthink these and try to take short-cuts mentioned above, such as using mnemonic devices and mathematical systems).
To develop left-hand rhythmic skills, especially the raising and lowering of fingers separately from right-hand rhythmic skills at the beginning.
To listen and move to a wider range of music as students advance, including music that divides into both duple and triple feels. Students will learn best when they can easily discern the differences between those two basic divisions.
To practice reading rhythm patterns that do not contain any other information (such as tonal material, key signatures, etc.) on a single line.
The two examples below, taken from Sound Innovations: Creative Warm-Ups, are helpful examples. The first shows three different systems for keeping track of beat and pulse: traditional counting, Gordon, and Takadimi. My preference for Gordon or Takadimi is listed above, though I do believe the use of numbers is helpful in later years when you are communicating with a larger group (e.g., “Would everyone please start on the third beat of measure 47?”).
The second example shows specific rhythm patterns and a sequence for developing rhythm skills that reflects the brain processes shown above:
Don’t be discouraged if your students don’t develop rhythmic skills immediately. It takes time! The key is to be patient and make sure that you really focus on teaching but one thing at a time.