Charts as Arguments

A chart makes one claim. Choose a type, title the claim, and keep it linked to the data.

This week

Week 5 · Excel Ch. 3 · Excel Project 5. Next: datasets and Tables (lecture 6).

After this lecture you should be able to

State the one claim a chart is supposed to support
Match that claim to a chart type (column, bar, line, scatter — and when not pie)
Title axes and the chart with words a reader can check against the sheet
Paste into Word or PowerPoint as a linked object when the story should update

Not decoration

Bad title: Chart 1, Attendance, Sheet1
Better title: Club events: film nights drew more attendees than workshops in September
If you cannot finish that sentence, you are not ready to Insert → Chart
The data rectangle from lecture 2 is the evidence; the chart is the argument (GE Goal 1c / 1d)

Question → series → chart

flowchart LR
  Q[Question] --> R[Summary range or Table]
  R --> C[Chart]
  C --> S[One sentence under the chart]

Often you chart a summary (COUNTIF of Review vs OK), not every student ID
A column of 40 names is a table, not a chart
Last week’s Status column is a good source for a two-bar comparison

Start from the comparison

You want to show	Usually use	Avoid
Categories vs a number	Column or bar	3-D column
Change over time	Line (time on x)	Category axis that is not in order
Relationship of two numbers	Scatter	Line connecting unordered IDs
Parts of one whole, few slices	Pie, maybe	Pie for many categories or for comparing two years
Distribution	Histogram / box (if available)	A pie of bins you made by hand without saying so

Pie charts are a special case

Combo charts and two axes

Honest defaults

Start column/bar axes at zero unless you have a written reason not to
Time goes left → right; sort the Table first
One color story: data vs highlight, not a rainbow of categories
Gridlines light; data labels only when they do not collide
Excel Ch. 3: chart styles and layouts are costumes — they do not fix a wrong type

Sparklines

Source and refresh

Click the chart: which range is highlighted?
If you add rows, a Table as the source (next lecture) expands; a static A1:B6 does not
Moving a chart to a Charts sheet is fine; keep the data on Data

Linked vs picture

Linked (Paste Special → keep source formatting / link): updates when the workbook changes
Picture: a frozen snapshot — use when you email a deck without the .xlsx
Say in a footnote which one you used
Never type a number on a slide that is not in the workbook

Caption in Word

Lab 5 — Chart one claim

From the gradebook or event Table, build a two-column summary (Status Count) with COUNTIF
Insert a clustered column chart (not 3-D, not pie)
Chart title = the claim in words
Vertical axis title = Number of students (or events)
Move the chart to a Charts sheet; leave the summary next to the data or on Summary
Paste the chart into a blank PowerPoint slide as a link; change one source count; refresh and confirm the slide intent
In Word, write the caption sentence including one limitation

Lab 5b — A chart that should not exist

Chart every student ID vs weighted total as a pie
Write three reasons this fails (part-whole? too many slices? IDs are not a composition?)
Replace it with a column of counts or a histogram-style bin chart if you have bins

Discussion

Designate a note-taker
When is a table clearer than a chart?
If Copilot “makes a chart,” what do you inspect first: type, source range, or title?

Carry these into Tables week

One claim per chart; title the claim
Type follows the comparison; pie is rarely the answer
Link to Word/PowerPoint when the numbers still live in Excel
Next lecture: Tables so charts, filters, and formulas keep up when rows are added

Placeholder notes for expansion