diff --git a/_includes/lab3.html b/_includes/lab3.html
index 461185c..b4b849c 100644
--- a/_includes/lab3.html
+++ b/_includes/lab3.html
@@ -228,7 +228,7 @@ <h1 data-number="1" id="goals"><span
          signals. Filters are a tool that remove (cut) signals and noise
          of certain frequencies, and preserve (pass) signals of other
          frequencies. For example, the signal of interest may be at a
-         particular frequncy, as in an NMR (nuclear magnetic resonance)
+         particular frequency, as in an NMR (nuclear magnetic resonance)
          experiment, or it may be an electrical pulse from a single
          photon detector. The background generally contains thermal
          noise from the transducer and amplifier, pick up of <span
@@ -1454,7 +1454,7 @@ <h3 data-number="7.2.2" id="sec:vd-freq"><span
          <ol type="1">
          <li><p>According to your model, what is the frequency
          dependence of the voltage divider? I.e. how should the transfer
-         function behave as a function of frequncy?</p></li>
+         function behave as a function of frequency?</p></li>
          <li><p>Connect the signal from the function generator to the
          input of the voltage divider.</p></li>
          <li><p>Measure the transfer function (attenuation) <span
diff --git a/_includes/lab4.html b/_includes/lab4.html
index 026023d..9f10e42 100644
--- a/_includes/lab4.html
+++ b/_includes/lab4.html
@@ -1233,15 +1233,19 @@ <h2 data-number="6.2" id="voltage-buffer"><span
          </div>
          <ol type="1">
          <li><p>Build the voltage follower using the function generator
-         as <span class="math inline">\(V_\text{in}\)</span>. You will
-         use the same settings as before (<span
-         class="math inline">\(400\text{ mV}_\text{pp}\)</span> sine
-         wave at <span class="math inline">\(432\text{ Hz}\)</span>).
-         Figure <a href="#fig:op-amp-test">15</a> shows a schematic of
-         the full set up using Channel 1 to measure <span
+         as <span class="math inline">\(V_\text{in}\)</span>, set to a
+         <span class="math inline">\(400\text{ mV}_\text{pp}\)</span>
+         sine wave at <span class="math inline">\(432\text{ Hz}\)</span>
+         (like we did in Lab 2). Figure <a
+         href="#fig:op-amp-test">15</a> shows a schematic of the full
+         set up using Channel 1 to measure <span
          class="math inline">\(V_\text{in}\)</span>, Channel 2 to
          measure <span class="math inline">\(V_\text{out}\)</span>, and
-         Channel 4 to trigger on the <em>Sync</em> output.</p></li>
+         Channel 4 to trigger on the <em>Sync</em> output. <strong>You
+         should use an oscilloscope probe for this measurement</strong>
+         (and probably all oscilloscope measurements for the rest of
+         your electronics career, but certainly for this
+         course).</p></li>
          <li><p>Confirm the gain is <span
          class="math inline">\(1\)</span>. If the gain is <span
          class="math inline">\(10\)</span> or <span
diff --git a/raw-content/lab3-raw.md b/raw-content/lab3-raw.md
index 0645952..d08c87c 100644
--- a/raw-content/lab3-raw.md
+++ b/raw-content/lab3-raw.md
@@ -19,7 +19,7 @@ You will learn to model the frequency dependence and effects on phase of passive
 
 You will also learn how to refine the oscilloscope measurement to reduce the effect of coax capacitance.
 
-Filters are incredibly important components in physical experiments. Often times your experimental goal is to detect an electronic signal hidden in a background of noise and unwated signals. Filters are a tool that remove (cut) signals and noise of certain frequencies, and preserve (pass) signals of other frequencies. For example, the signal of interest may be at a particular frequncy, as in an NMR (nuclear magnetic resonance) experiment, or it may be an electrical pulse from a single photon detector. The background generally contains thermal noise from the transducer and amplifier, pick up of $60\text{ Hz}$ wall power, transients from machinery, radiation from radio, TV stations, light sources, cell phones, and so forth. The purpose of filtering is to enhance the signal of interest by recognizing its characteristic time dependence and to reduce the unwanted background to the lowest possible level. A radio does this when you tune to a particular station, using a resonant circuit to only allow a narrow band of frequency through (the center frequency of this band is *the station*). The signal you want may be less than $10^{-6}$ of the total radiation power at your antenna, yet you get a high-quality signal from the selected station due to the filtering. Many experiments require specific filters designed so that the signal from the phenomenon of interest lies in the pass-band of the filter, while the attenuation bands are chosen to suppress the background and noise.
+Filters are incredibly important components in physical experiments. Often times your experimental goal is to detect an electronic signal hidden in a background of noise and unwated signals. Filters are a tool that remove (cut) signals and noise of certain frequencies, and preserve (pass) signals of other frequencies. For example, the signal of interest may be at a particular frequency, as in an NMR (nuclear magnetic resonance) experiment, or it may be an electrical pulse from a single photon detector. The background generally contains thermal noise from the transducer and amplifier, pick up of $60\text{ Hz}$ wall power, transients from machinery, radiation from radio, TV stations, light sources, cell phones, and so forth. The purpose of filtering is to enhance the signal of interest by recognizing its characteristic time dependence and to reduce the unwanted background to the lowest possible level. A radio does this when you tune to a particular station, using a resonant circuit to only allow a narrow band of frequency through (the center frequency of this band is *the station*). The signal you want may be less than $10^{-6}$ of the total radiation power at your antenna, yet you get a high-quality signal from the selected station due to the filtering. Many experiments require specific filters designed so that the signal from the phenomenon of interest lies in the pass-band of the filter, while the attenuation bands are chosen to suppress the background and noise.
 
 There are 4 basic kinds of filters:
 
@@ -717,7 +717,7 @@ The bridge uses an AC voltage to make the measurement, and often components are
 
 In this experiment, you will test the frequency response of the voltage divider.
 
-1. According to your model, what is the frequency dependence of the voltage divider? I.e. how should the transfer function behave as a function of frequncy?
+1. According to your model, what is the frequency dependence of the voltage divider? I.e. how should the transfer function behave as a function of frequency?
 
 2. Connect the signal from the function generator to the input of the voltage divider.
 
diff --git a/raw-content/lab4-raw.md b/raw-content/lab4-raw.md
index f540dc7..1bcb37d 100644
--- a/raw-content/lab4-raw.md
+++ b/raw-content/lab4-raw.md
@@ -438,7 +438,7 @@ You will use the buffer to take the output of the function generator (with a $50
 
 ![Test and measurement setup for op-amp circuits](../resources/lab4fig/op-amp-test.png){#fig:op-amp-test width="15cm"} 
 
-1.  Build the voltage follower using the function generator as $V_\text{in}$. You will use the same settings as before ($400\text{ mV}_\text{pp}$ sine wave at $432\text{ Hz}$). Figure @fig:op-amp-test shows a schematic of the full set up using Channel 1 to measure $V_\text{in}$, Channel 2 to measure $V_\text{out}$, and Channel 4 to trigger on the *Sync* output.
+1.  Build the voltage follower using the function generator as $V_\text{in}$, set to a $400\text{ mV}_\text{pp}$ sine wave at $432\text{ Hz}$ (like we did in Lab 2). Figure @fig:op-amp-test shows a schematic of the full set up using Channel 1 to measure $V_\text{in}$, Channel 2 to measure $V_\text{out}$, and Channel 4 to trigger on the *Sync* output. **You should use an oscilloscope probe for this measurement** (and probably all oscilloscope measurements for the rest of your electronics career, but certainly for this course).
 
 2.  Confirm the gain is $1$. If the gain is $10$ or $0.1$, this is likely due to a setting on the oscilliscope (ask for help if you're lost).