diff --git a/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 b/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
index 52d08e9ef..4407bc0ba 100644
--- a/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
+++ b/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* :
+!!!! 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)
+
* with real objects
