Add reading about signed numbers / two's complement (#1260)

common-content/en/module/tools/binary-and-hexidecimal-numbers/index.md

@@ -5,7 +5,7 @@ time = 90
 facilitation = false
 emoji= "📖"
 [objectives]
-    1="Convert numbers between any two of: binary, decimal, hexidecimal"
+    1="Convert signed and unsigned numbers between any two of: binary, decimal, hexadecimal"
     2="Explain the similarities and differences between binary, decimal, and hexidecimal numbers"
     3="Explain why we use binary numbers"
     4="Explain why we use hexidecimal numbers"
@@ -19,10 +19,12 @@ emoji= "📖"
 
 Read the learning objectives listed on this page: Bear in mind what you're trying to achieve while reading this text. If a topic isn't making much sense, and isn't in the objectives, you can probably skip over it. If a topic is listed in the objectives, you should keep studying it until you are confident you've met the objective.
 
-Read chapters 1 and 2 of How Computers Really Work.
+{{<note type="Reading">}}
+Read chapters 1 and 2 of How Computers Really Work. You can skip the Binary Logic section (but feel free to read it if you're curious).
 
-You can skip the Binary Logic section (but feel free to read it if you're curious).
+Also read the "Binary Addition", "Signed Numbers" and "Unsigned Numbers" sections from chapter 5. You can skip the "Half Adders", "Full Adders", and "A 4-bit Adder" sections.
 
-Do every exercise listed in the chapters.
+Do every exercise listed in the chapters. You can skip the projects.
+{{</note>}}
 
 Check you have achieved each learning objective listed on this page.