Based on my research, what I think you are referring to is a sketch similar to the work of Robert Baden-Powell. He was the founder of the world scouting movement and he was also an artist. He famously illustrated his own published works such as Scouting for Boys and other scouting guidebooks. His sketches are sometimes referred to as ‘Gilwell sketches’ referring to the site where scouts receive training to earn their ‘wood badge’
You asked how to create one.
Robert Baden-Powell’s sketches were made mostly with pen and ink but some were made with watercolors.
They had very minimal backgrounds, often only a line or two to indicate the horizon
They portrayed scouts doing scouting activities in small groups or by themselves.
If I was trying to create my own, here’s what I would do: I would have some of my friends pose for me doing a particular scouting activity such as setting up a tent. Then I would take a digital photograph, print it out, and then trace the basic outline of the figures using tracing paper. I would use this as a reference to draw my own sketch in ink.
To see some examples of sketches by Baden-Powell go to the Scouter’s Library of Clipart and Resources at http://clipart.usscouts.org/library/.