diff --git a/tools/combine_pkg_envs.jl b/tools/combine_pkg_envs.jl
index a815994f..91cd9258 100644
--- a/tools/combine_pkg_envs.jl
+++ b/tools/combine_pkg_envs.jl
@@ -1,8 +1,10 @@
-if !isdir("pluto-deployment-environment") || length(ARGS) != 1
+include("./common.jl")
+
+if length(ARGS) != 1
     error("""
-    Run me from the root of the repository directory, using:
+    Syntax:
 
-    julia tools/combine_pkg_envs.jl <update (true or false)>
+    julia tools/$(basename(@__FILE__)) <update (true or false)>
 
     Where <update> is true or false to update all packages as well.
     """)
@@ -10,34 +12,6 @@ end
 
 update = parse(Bool, ARGS[1])
 
-import Pkg
-Pkg.activate("./pluto-deployment-environment")
-Pkg.instantiate()
-import Pluto
-ENV["JULIA_PKG_PRECOMPILE_AUTO"] = 0
-
-
-
-# Find all notebooks
-lectures_dir = joinpath(@__DIR__, "..", "lectures")
-prob_prog_dir = joinpath(@__DIR__, "..", "probprog")
-minis_dir = joinpath(@__DIR__, "..", "minis")
-ignore_dir = joinpath(@__DIR__, "..", "ignore_dir")
-
-all_notebooks = mapreduce(union, [
-    lectures_dir, 
-    prob_prog_dir, 
-    minis_dir,
-    ignore_dir
-]) do d
-    isdir(d) ? 
-        filter(Pluto.is_pluto_notebook, readdir(d; join=true)) : 
-        String[]
-end
-
-
-
-
 "Extract embedded project and manifest contents from each notebook"
 function extract_toml_contents(notebook_path::String)
     content = read(notebook_path, String)
diff --git a/tools/common.jl b/tools/common.jl
new file mode 100644
index 00000000..10260bb2
--- /dev/null
+++ b/tools/common.jl
@@ -0,0 +1,41 @@
+if !isdir("pluto-deployment-environment")
+    error("""
+    Run me from the root of the repository directory, using:
+
+    julia tools/scriptname.jl argument1 argument2 ...
+    """)
+end
+
+
+begin
+    import TOML
+    manifest_version = TOML.parsefile("./pluto-deployment-environment/Manifest.toml")["julia_version"]
+    
+    @assert manifest_version == string(VERSION) "This repository uses Julia version $(manifest_version) (in pluto-deployment-environment), but this is Julia $(VERSION). Start a new Julia session with the correct version, or create a new Manifest.toml."
+end
+
+import Pkg
+Pkg.activate("./pluto-deployment-environment")
+Pkg.instantiate()
+import Pluto
+ENV["JULIA_PKG_PRECOMPILE_AUTO"] = 0
+
+flatmap(args...) = vcat(map(args...)...)
+
+
+# Find all notebooks
+lectures_dir = joinpath(@__DIR__, "..", "lectures")
+prob_prog_dir = joinpath(@__DIR__, "..", "probprog")
+minis_dir = joinpath(@__DIR__, "..", "minis")
+ignore_dir = joinpath(@__DIR__, "..", "ignore_dir")
+
+all_notebooks = mapreduce(union, [
+    lectures_dir, 
+    prob_prog_dir, 
+    minis_dir,
+    ignore_dir
+]) do d
+    isdir(d) ? 
+        filter(Pluto.is_pluto_notebook, readdir(d; join=true)) : 
+        String[]
+end
diff --git a/tools/find_open_markdown_cells.jl b/tools/find_open_markdown_cells.jl
new file mode 100644
index 00000000..7932d3eb
--- /dev/null
+++ b/tools/find_open_markdown_cells.jl
@@ -0,0 +1,21 @@
+include("./common.jl")
+
+
+for path in all_notebooks
+    @info "🌸 Checking $path"
+    notebook = Pluto.load_notebook_nobackup(path)
+    
+    
+    old = notebook.topology
+    new = notebook.topology = Pluto.updated_topology(old, notebook, notebook.cells)
+    
+    
+    for c in notebook.cells
+        c.code_folded && continue
+        !Pluto.is_just_text(new, c) && continue
+        if startswith(strip(c.code), "md") || startswith(strip(c.code), "html")
+            @error "Markdown cell is not folded" path c.cell_id
+        end
+    end
+    
+end
diff --git a/tools/generate_pdf.jl b/tools/generate_pdf.jl
index dfe498a3..6137be3b 100644
--- a/tools/generate_pdf.jl
+++ b/tools/generate_pdf.jl
@@ -29,14 +29,12 @@ output_dir = mktempdir(; cleanup=false)
 @info "Output directory: $(output_dir)"
 
 lecture_urls = [
-    "TODO You need to update this list",
     "https://bmlip.github.io/course/lectures/Course%20Syllabus.html",
     "https://bmlip.github.io/course/lectures/Machine%20Learning%20Overview.html",
     "https://bmlip.github.io/course/lectures/Probability%20Theory%20Review.html",
     "https://bmlip.github.io/course/lectures/Bayesian%20Machine%20Learning.html",
     "https://bmlip.github.io/course/lectures/Factor%20Graphs.html",
     "https://bmlip.github.io/course/lectures/Density%20Estimation.html",
-    "https://bmlip.github.io/course/lectures/The%20Multinomial%20Distribution.html",
     "https://bmlip.github.io/course/lectures/Regression.html",
     "https://bmlip.github.io/course/lectures/Generative%20Classification.html",
     "https://bmlip.github.io/course/lectures/Discriminative%20Classification.html",
diff --git a/tools/update_notebook_packages.jl b/tools/update_notebook_packages.jl
index 5250f070..61685b6a 100644
--- a/tools/update_notebook_packages.jl
+++ b/tools/update_notebook_packages.jl
@@ -1,4 +1,6 @@
-if !isdir("pluto-deployment-environment") || length(ARGS) != 2
+include("./common.jl")
+
+if length(ARGS) != 2
     error("""
     Run me from the root of the repository directory, using:
 
@@ -9,33 +11,14 @@ if !isdir("pluto-deployment-environment") || length(ARGS) != 2
     """)
 end
 
-begin
-    import TOML
-    manifest_version = TOML.parsefile("./pluto-deployment-environment/Manifest.toml")["julia_version"]
-    
-    @assert manifest_version == string(VERSION) "This repository uses Julia version $(manifest_version) (in pluto-deployment-environment), but this is Julia $(VERSION). Start a new Julia session with the correct version, or create a new Manifest.toml."
-end
-
-import Pkg
-Pkg.activate("./pluto-deployment-environment")
-Pkg.instantiate()
-
-import Pluto
-
-flatmap(args...) = vcat(map(args...)...)
+level = getfield(Pkg, Symbol("UPLEVEL_$(ARGS[1])"))
+run_notebooks = parse(Bool, ARGS[2])
 
 
 getfrom(dir) = flatmap(walkdir(dir)) do (root, _dirs, files)
     joinpath.((root,), files)
 end
 
-all_files_recursive = [getfrom("lectures")..., getfrom("probprog")..., getfrom("minis")...]
-
-all_notebooks = filter!(Pluto.is_pluto_notebook, all_files_recursive)
-
-level = getfield(Pkg, Symbol("UPLEVEL_$(ARGS[1])"))
-run_notebooks = parse(Bool, ARGS[2])
-
 for n in all_notebooks
     @info "Updating" n
     ENV["JULIA_PKG_PRECOMPILE_AUTO"] = 0