MathElf's whiteboard is a great tool for tutors and students to work together. One great way to get your students more involved in sessions and more excited about MathElf is to encourage them to write on the whiteboard.
Try to work this into your session as you go through the problem together. Ask the student to write out what they'd get when they complete a calculation or write the formula to use in the next step.
If your student is struggling to write on the whiteboard, or would prefer to write on their own paper, it's fine if you take over doing the majority of the writing for them instead.
It can also be helpful, especially for making points on graphs or labeling diagrams, to point out that students can zoom in on the screen using a two-finger pinch (like you would for a picture).