learn: Document StarterBot for Technic and BOOST.

learn/building-a-robot/boost/index.md

@@ -15,8 +15,27 @@ gallery:
     title: "You could build a swivel wheel or simply use a rounded element for the robot to lean on."
 ---
 
+The BOOST Move Hub is unique because it has two motors builtin already. You can
+use these to make a BOOST variant of the StarterBot very quickly.
+You can also use one of the standard robots using the instructions that come
+with the kit.
+
 {% include scaled.html path="/learn/building-a-robot/boost/starterbot-boost.jpg" %}
 
+# How to build it 
 
+The hub is placed upright in this design. This ensures that most of the weight
+of the motors and batteries rests on the powered wheels. This creates extra
+grip, which makes its movements much more accurate.
 
 {% include gallery %}
+
+You can adjust the design if you want to use bigger wheels. The BOOST set also
+contains many elements to make this quick build look a bit more interesting.
+
+# Adding sensors
+
+The BOOST set comes with
+the {% include setlink.html id=88007 %} which works well for most of the
+lessons. By mounting it on the robot as shown above, you can easily tilt it to
+face either downward or forward, depending on the application at hand.

learn/building-a-robot/index.md

@@ -8,8 +8,9 @@ header:
 ---
 
 Building a vehicle robot is a great way to get familiar with robotics and
-coding. We'll show you how to build one using SPIKE, MINDSTORMS, Technic, City,
-or BOOST. 
+coding. A basic robot consists of two wheels, each powered by a motor, and a
+support in the back. We'll show you how to build such a robot using SPIKE,
+MINDSTORMS, Technic, City, or BOOST.
 
 **Tip** ⸺ You can also use your own design or competition robot. You'll learn
 to adapt the code to your design along the way. However, it can be

learn/building-a-robot/technic/index.md

@@ -15,7 +15,43 @@ header:
   teaser: /learn/building-a-robot/technic/starterbot-technic-distance.jpg
 ---
 
+The Technic Hub is internally very similar to the SPIKE Prime Hub. This means
+you can follow along with almost every lesson without changes.
+
 {% include scaled.html path="/learn/building-a-robot/technic/starterbot-technic-line.jpg" %}
 
+You can build your StarterBot with one Technic Hub, two
+[motors](/learn/getting-started/what-do-you-need/#choosing-motors) and one or
+two sensors. This page shows some pictures for inspiration, but you can build
+something similar with the pieces already in your collection.
+
+# Building a base
+
+A robot drive base consists of two wheels, each powered by one motor, and a
+support wheel in the back. The motors pictured above make it very easy to mount
+the Technic hub directly on top. If you have other motors, you can use gears to
+drive the wheels if needed.
+
+You can use any type of wheel. Later on, you'll set up the
+code to match the wheel size and width of your robot. 
 
 {% include gallery %}
+
+# The support wheel
+
+The rear of the robot has to be supported so it can move freely. You
+could use:
+- A swivel wheel as pictured above (see [instructions](/learn/building-a-robot/mindstorms-inventor/starterbot-inventor-05.png))
+- A ball caster (see the [SPIKE variant](/learn/building-a-robot/spike-prime/))
+- A sliding contact (see the [City variant](/learn/building-a-robot/city/))
+
+# Adding sensors
+
+You can use the same sensors as used on
+the [SPIKE Prime](/learn/building-a-robot/spike-prime/) StarterBot if you
+already have them, but
+the {% include setlink.html id=88007 %} is generally the more affordable option.
+
+It can measure color as well as rough distance, which makes it
+quite versatile. You can mount it facing downward or forward, depending on the
+application. You could also use two of these sensors at the same time.