Do you have your viewfinder built yet? A piece of overhead transparency or plexiglass that you have attached to some cardboard to make it stiffer.
Now is time to put it in practice. So you have a transparent page. Draw a line midway through the top with your permanent marker, to divide the top in half top and do the same to the other
Repeat those lines on your drawing pad, cut it in half to end up with 4 sections.
Pick something not too intricate for your drawing today. You could pick your hand if you're not sick of it yet, or another object,
If you choose your left hand, position the viewfinder on top of your hand which is turned over with the fingers facing up.
If you pick an object, place your viewfinder so that your object sits in the middle of the viewfinder.
Close one eye. (Not both!!!!) By closing one eye, you flatten the depth of field that is achieved with our two eyes seeing at the same time. It then becomes easier to render on a flat surface what you see with one eye, which tends to flatten what you see.
With a NON permanent marker, like a sharpie, start drawing ON the viewfinder. Draw what you see. Cheating? OK. Call it what you want, that's the exercise for today, lol.
Use the lines splitting the viewfinder to guide you to reproduce the SHAPES and angles that you see on the viewfinder. on your paper. Using your right mode of drawing, you are reproducing shapes and spaces as they appear in relation to the various lines through the viewfinder.
When your drawing ON the viewfinder is pretty close to your satisfaction, put the viewfinder next to your drawing pad, and reproduce the lines, shapes and angles from the viewfinder on your drawing pad, which is divided into the same lines as the viewfinder.
When you are finished, erase the middle lines on your drawing pad, and assess your drawing against the original.
Remember to date it, and post it on the 'sketchbook project' site.
If you have questions, contact me on firstname.lastname@example.org