All of your students in a class will have access to the same content, based on your settings under Class Content. So first make sure you have the content in the summary section turned on. The only reason a specific student would not be able to get to or see a content item especially the Summary, which is at the bottom of the navigation, would be a scrolling issue based on their screen size.
If the screens they are using are smaller (like a tablet) the left navigation menu may take up the whole height of the screen. If that is the case the Summary section may be down off the screen. When they click on Summary the summary section gets expanded down on the menu, so they may need to just scroll down again in the left menu for them to see the Review and Post-test options. Alternatively they can try changing their browser zoom to make everything smaller on the screen. That should make the menu take up less space allowing the last items to be seen.