Sometimes it is necessary to trace (parts of) an existing image or own drawing. In broad daylight/on a sunny day, this works perfectly against a window. You don’t need a light box or special tracing paper.
Step 1: Attach the original you want to trace to the window. Two adhesive tapes at the top are enough (preferably with adhesive tape that can be removed easily). Choose tape that can be easily removed (e.g. Scotch).

Step 2: Attach the drawing paper with two adhesive tapes over your original on the window. Sunlight outside now allows you to see your original through it, even if you use thicker drawing paper. Do not forget to carefully remove the adhesive tape afterwards. If it’s too dark outside, you need a light box. These are nowadays nice and flat, in different sizes and with energy efficient LED light.

Exercise: choose a drawing/image and try to trace parts of it against a window.