suite.. et fin pour cette partie overview en anglais? avant de profond...

suite.. et fin pour cette partie overview en anglais? avant de profond changements ultérieurs en équipe :)

01.curriculum/01.physics-chemistry-biology/02.Niv2/04.optics/04.use-of-basic-optical-elements/01.plane-refracting-surface/02.plane-refracting-surface-overview/cheatsheet.en.md

@@ -210,6 +210,20 @@ in Figures 3 and 4, and 5 and 6 below, and review NOTE 1.
 
 #### Examples of graphical situations, with analytical results to train
 
+!!!! *IMPORTANT* :<br>
+!!!! Even for only one of the following figures, the real or virtual character of the
+!!!! image may depend on the position of the object. This paragraph is only for you 
+!!!! to understand how to determine the 3 rays that determine the image. It is 
+!!!! important not to memorize these figures, which would be limiting, misleading 
+!!!! and without interest.
+!!!!
+!!!! All the useful numerical values are given for each figure, making it possible 
+!!!! also to check that you master the analytical study of each presented case.
+!!!!
+
+
+[Click here for geogebra animation](https://www.geogebra.org/material/iframe/id/gvkqgrpe)<br>
+
 * with real objects
 
 ![](thin-spherical-surface-1.png)<br>