diff --git a/sessions/dplyr-joins.qmd b/sessions/dplyr-joins.qmd
index 47dfd45..a53f856 100644
--- a/sessions/dplyr-joins.qmd
+++ b/sessions/dplyr-joins.qmd
@@ -629,6 +629,49 @@ library(fs)
 source(here("R/functions.R"))
 ```
 
+Making sure to have the `download.file()` commented out, we'll include
+some code to delete the created `data-raw/mmash/` folder so this script
+can run cleanly each time. Place the code right below where the
+`download.file()` code is.
+
+<!-- TODO: Remove this after course ends, since the same info is in pre-course now -->
+
+```{r data-raw-mmash-comment-out}
+#| filename: "data-raw/mmash.R"
+#| eval: false
+# Download
+mmash_link <- "https://physionet.org/static/published-projects/mmash/multilevel-monitoring-of-activity-and-sleep-in-healthy-people-1.0.0.zip"
+# download.file(mmash_link, destfile = here("data-raw/mmash-data.zip"))
+
+# Remove previous `mmash/` folder to have clean update
+dir_delete(here("data-raw/mmash/"))
+```
+
+Next, as we have altered `import_multiple_files()` to use
+`file_path` instead of `file_path_id`, we'll need to update how we
+`group_by()` when creating `summarised_rr_df` and 
+`summarised_actigraph_df`.
+
+```{r data-raw-mmash-update}
+#| filename: "data-raw/mmash.R"
+summarised_rr_df <- rr_df |>
+    group_by(user_id, day) |>
+    summarise(across(ibi_s, list(
+        mean = \(x) mean(x, na.rm = TRUE),
+        sd = \(x) sd(x, na.rm = TRUE)
+    ))) |>
+    ungroup()
+
+summarised_actigraph_df <- actigraph_df |>
+    group_by(user_id, day) |>
+    summarise(across(hr, list(
+        mean = \(x) mean(x, na.rm = TRUE),
+        sd = \(x) sd(x, na.rm = TRUE)
+    ))) |>
+    ungroup()
+  reduce(full_join)
+```
+
 Go into the `doc/learning.qmd` and cut the code used to create the
 `saliva_with_day_df` as well as the code to `full_join()` all the
 datasets together with `reduce()` and paste it at the bottom of the