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+% https://git.betalupi.com/Mark/latex-packages
+% use [nosolutions] flag to hide solutions.
+% use [solutions] flag to show solutions.
+% Last built with version 1.1.0
+\documentclass[
+	nosolutions,
+	singlenumbering
+]{ormc_handout}
+
+% We put nodes in a separate layer, so we can
+% slightly overlap with paths for a perfect fit
+\pgfdeclarelayer{nodes}
+\pgfsetlayers{main,nodes}
+
+% Layer settings
+\tikzset{
+	% Layer hack, lets us write
+	% later = * in scopes.
+	layer/.style = {
+		execute at begin scope={\pgfonlayer{#1}},
+		execute at end scope={\endpgfonlayer}
+	}
+}
+
+\begin{document}
+
+	\maketitle
+		{The Electrician's Warm-Up}
+		{Prepared by Mark on \today}
+
+	Ivan the electician is working in an apartment. He has a box of switches, which come in three types:
+	\begin{center}
+		\begin{minipage}[t]{0.3\textwidth}
+			\begin{center}
+			Plain switch
+			\end{center}
+			\begin{center}
+			\begin{tikzpicture}
+				% A state
+				\node at (0.375, -1.25) {A};
+				\draw[line width=1mm] (0, 0) -- (0.75, 0);
+
+				\draw[fill=white] (0, 0) circle (1mm);
+				\draw[fill=white] (0.75, 0) circle (1mm);
+
+				% B state
+				\node at (2.375, -1.25) {B};
+				\draw[line width=1mm,cap=round] (2, 0) -- (2.6, 0.4);
+
+				\draw[fill=white] (2, 0) circle (1mm);
+				\draw[fill=white] (2.75, 0) circle (1mm);
+			\end{tikzpicture}
+			\end{center}
+		\end{minipage}
+		\begin{minipage}[t]{0.3\textwidth}
+			\begin{center}
+			Three-way switch
+			\end{center}
+			\begin{center}
+			\begin{tikzpicture}
+				% A state
+				\node at (0.375, -1) {A};
+				\draw[line width=1mm] (0, 0) -- (0.75, 0.5);
+
+				\draw[fill=white] (0, 0) circle (1mm);
+				\draw[fill=white] (0.75, 0.5) circle (1mm);
+				\draw[fill=white] (0.75, -0.5) circle (1mm);
+
+				% B state
+				\node at (2.375, -1) {B};
+				\draw[line width=1mm] (2, 0) -- (2.75, -0.5);
+
+				\draw[fill=white] (2, 0) circle (1mm);
+				\draw[fill=white] (2.75, 0.5) circle (1mm);
+				\draw[fill=white] (2.75, -0.5) circle (1mm);
+			\end{tikzpicture}
+			\end{center}
+		\end{minipage}
+		\hfill
+		\begin{minipage}[t]{0.3\textwidth}
+			\begin{center}
+				Four-way switch
+			\end{center}
+			\begin{center}
+			\begin{tikzpicture}
+				% A state
+				\node at (0.375, -0.5) {A};
+				\draw[line width=1mm] (0, 0) -- (0.75, 1);
+				\draw[line width=1mm] (0, 1) -- (0.75, 0);
+
+				\draw[fill=white] (0, 0) circle (1mm);
+				\draw[fill=white] (0.75, 0) circle (1mm);
+				\draw[fill=white] (0, 1) circle (1mm);
+				\draw[fill=white] (0.75, 1) circle (1mm);
+
+				% B state
+				\node at (2.375, -0.5) {B};
+				\draw[line width=1mm] (2, 0) -- (2.75, 0);
+				\draw[line width=1mm] (2, 1) -- (2.75, 1);
+
+				\draw[fill=white] (2, 0) circle (1mm);
+				\draw[fill=white] (2.75, 0) circle (1mm);
+				\draw[fill=white] (2, 1) circle (1mm);
+				\draw[fill=white] (2.75, 1) circle (1mm);
+			\end{tikzpicture}
+			\end{center}
+		\end{minipage}
+	\end{center}
+
+	When a switch is pointing up, it is in the \say{A} state. When it is pointing down, it is in the \say{B} state. Each circle represents a terminal on the switch, and lines represent electrical connections.
+
+	\example{}
+	First, Ivan wires a simple light in the kitchen: one switch, one lamp. The result is the following circuit:
+
+	\begin{center}
+	\begin{tikzpicture}
+
+		\begin{scope}[layer = nodes]
+
+			\draw[fill=white] (-1.5, 0) circle (1mm);
+
+			\node (h) at (-2, 0) {\texttt{Hot}};
+
+			\draw[fill=white] (0, 0) circle (1mm);
+			\draw[fill=white] (0.75, 0) circle (1mm);
+
+			\node[
+				circle,
+				draw = black,
+				fill = white,
+				label = below:\texttt{Lamp}
+			] (l) at (2,0) {$\circledast$};
+
+			\draw[fill=white] (3.5, 0) circle (1mm);
+
+			\node (n) at (4.5, 0) {\texttt{Neutral}};
+
+		\end{scope}
+
+		\draw[line width=1mm,cap=round] (-1.5, 0) -- (0, 0);
+		\draw[line width=1mm,cap=round] (0, 0) -- (0.6, 0.4);
+		\draw[line width=1mm,cap=round] (0.75, 0) -- (l);
+		\draw[line width=1mm,cap=round] (l) -- (3.5,0);
+	\end{tikzpicture}
+	\end{center}
+
+	\problem{}
+	Ivan now needs to wire a hallway. It has two switches, one at each end. Toggling either switch should toggle the single lamp in the middle. Which switches should Ivan use, and how should he connect their terminals?
+
+	\vfill
+
+
+	\problem{}
+	Next, Ivan goes to the bedroom. There is one switch by the door and one on each side of the bed. How can he make these three switches control one lamp?
+
+	\vfill
+
+	\problem{Bonus}
+	Is it possible to do the same with four or more switches? If so, how?
+\end{document}
\ No newline at end of file