Run Button Not Visible on App

Student is in Lesson 5-6 and the run button does not appear on his screen. Any suggestions? He is using a Chrome book. Other students have the button. This is occuring in Unit 1 -Problem Solving/Lessons 5 and Lesson 6.

Nevermind. I figured it out. If students are zoomed in 100% on some devices they will not see the run button. I asked the student to decrease to 75% and the student could then see the run button.