The Page Template, and the similar looking templates used for posts, were influenced by Scouts 4 WordPress but the underlying structure is pretty generic.
Scouts 4 WordPress uses a custom field to specify a fixed size image (540x200) at the top of each page and if it isn't defined an empty box is shown. It is only really the choice of image size that is particularly interesting. The Scouting Challenge theme uses the standard WordPress 'Featured Image' facility that is built into the page editor and links in with the Media Library. Any sized image may be used and it will automatically be rescaled so it is at most 740x555 (or 960x720 if there isn't a sidebar, or 520x390 if there are two).
A 540x200 image has almost exactly the same proportions as a 960x360 image (the exact correspondence would be 540x202) meaning an image used for the home page would also work on the pages. So it is actually a sensible design feature in that respect and there is also a lot to be said for having consistently sized pictures on each page. However for the Scouting Challenge theme the approach used is to leave the choice of the size and proportions of the image entirely to the user. A 960x360 image used on the page will automatically be resized to the appropriate 740x277 (or 520x195) but the typical 4:3 proportion from a digital camera will work fine.
It would be great if the theme used relative font sizes everywhere but it is a fixed width design and that causes issues. So those font sizes that really need to be fixed have been and the others remain relatively sized. The fixed sizes are actually in the Header, Footer and styled parts of the Sidebar. The main body font size is the user's own browser default, which is arguably how things should be done, even if many users probably might never touch their defaults. The 2012 Scouts brand guidelines said that Verdana should be used for body text on the web so that was reluctantly in use in the theme but the 2015 guidelines no longer mention it so it has been removed in version 4.0. The body text was typically bigger than in the Scouts 4 WordPress theme and that meant things got a bit cramped with left and right sidebars. So the design was stripped down to use just the one sidebar (but see below). This defaults to being on the right but there is an option to have it on the left if you want it (and users can override this choice using a cookie if the site administrator allows it). The default sidebar will use BreadCrumb NavXT if it is installed. It is a dynamic sidebar and in the screenshot is being used with the PS Subpages plugin widget. The stylesheet will style both plugins appropriately but in a relatively generic fashion so it may also work with other plugins
Links are displayed in Blue with underlining as that is similar to the typical browser default behaviour and it is always a good idea to avoid doing something unexpected. The links are highlighted in Orange for suitable contrast when active.
The sidebar may also include controls (shown in the above screenshot) to allow the user to choose whether to have the sidebar on the left or the right or to accept the site default. Whether these controls are shown or not is one of the theme options. The default is to show them.
Although the theme was designed with just the one sidebar in mind, it has been added to with a global option to allow you to have two sidebars or none at all if you would like. If you have two then the 'Second Sidebar', which is empty by default, will always be the one on the left.
There are also page templates to allow you to override the global defaults and force a page to have no sidebars, a sidebar on the left, a sidebar on the right or two sidebars. The template files in the theme are just placeholders and the theme will actually use the page.php template configured appropriately.
Similarly there is a template for a page with no sidebars and the 'slider' instead of any Featured Image.