What is a Venn diagram?
A diagram technique that represents sets as circles or boxes, using the shapes and their overlap to visualize what they share and where they differ.
It lets you lay out “only in A,” “only in B,” and “in both A and B” spatially, which makes it useful for comparing and classifying things.
ThinkTray uses rectangular group frames, since they’re easier to fit cards into. The look is different from the classic circular Venn diagram, but the underlying idea — using card membership and frame overlap to represent the relationship between sets — is the same.
Where this works well
- When you want to compare two or three things and make what they share and where they differ clear
- When you want to focus on the part that satisfies several conditions at once (the overlap)
- When you want to find, among cards you wrote out freely, the important items that span more than one theme
How to build it in ThinkTray
When building a Venn diagram in ThinkTray, drawing perfectly round circles matters less than the core idea: gather cards into “groups,” and let the same card belong to more than one group. Because a single card can belong to several groups at once, the frames that contain it overlap — and that overlap represents “this applies to both.”
The “Venn Diagram” folder in the demo above holds two diagrams representing two stages. “1-Venn Diagram” is the stage where you’ve just written ideas onto cards; “2-Venn Diagram” is the stage where those cards have been sorted into two overlapping groups. Open them in order to see the flow from loose cards to a finished Venn diagram.
Step 1: Write out cards first
Don’t decide “only A,” “only B,” or “both” up front. Just write down whatever comes to mind about your theme, one idea per card. It’s fine to place related cards near each other, roughly. You don’t need to create any groups at this stage.
In the demo, starting from the question “What matters when you think things through and communicate them?”, cards like “Think logically,” “Writing,” and “Have someone else check it” were written down. “1-Venn Diagram” shows this stage.
Step 2: Look at the cards and find categories
Look back over the cards you wrote and think about what natural groupings appear. Rather than forcing them into categories you decided beforehand, the key is to spot a shared perspective from the cards as they’re laid out.
In the demo, looking back over the cards revealed two clusters: “Deepen Thinking” and “Convey Thinking.” Cards that relate to only one move to the left or right; cards that relate to both move to the space between.
Step 3: Create the “Deepen Thinking” group
Select all the cards related to “Deepen Thinking.” At this point, also include cards that relate to both clusters, such as “Organize in logical order” and “In your own words.”
Right-click the selected cards and run “Group ▶” → “Create Group” to make your first group.
Step 4: Create the “Convey Thinking” group
Next, select the cards related to “Convey Thinking,” along with the same shared cards, and run “Create Group” again.
The shared cards already belong to the “Deepen Thinking” group, but they keep that membership while also joining the “Convey Thinking” group — you don’t need to make a separate card for the overlap.
Step 5: Check the overlap and revisit your categories
The outline of each group expands to enclose its members, so wherever a card belongs to both groups, the two outlines overlap. That overlapping area represents what relates to both “Deepen Thinking” and “Convey Thinking.” You can see the finished state in “2-Venn Diagram.”
As you look at the diagram, ask yourself “might this card relate to both?” or “does this one really belong to only one side?” and revisit where cards sit and which groups they belong to. Don’t treat your first categorization as final — rethinking it after creating the overlap is one of the points of using a Venn diagram.
Step 6: Style the frame color and add a name
Select a group and change its border color from the context toolbar. If you fill a group, the overlapping area gets hidden under whichever group’s color sits in front, so leaving the fill “transparent” keeps the overlap easy to see.
Double-click empty space inside a group (anywhere that doesn’t overlap a card) to type in a caption. In the demo, the two groups are named “Deepen Thinking” and “Convey Thinking.”
If you want to overlap three or more sets, repeat the same operation: select the relevant cards and create a group. For a worked example, see “3C Analysis and Cross 3C Analysis: find the strengths to grow from customer, company, and competitor.”
Tips
- Write first, sort later — Don’t try to finish your categories while you’re still writing cards; just get your thinking out first. Work out the categories once you can see the cards.
- Go back and forth between writing and sorting — Seeing a cluster take shape can spark new cards. Keep adding, moving, and re-assigning cards to groups as you go.
- You can build the frames first instead — If what you’re comparing is already fixed, like “customer” and “your company,” it’s fine to create the groups first and then drop cards into them.
- Add the shared card when creating both groups — Just include the same card in each selection when you create a group, and it ends up belonging to both.
- Place shared cards between the two clusters — Because a group’s outline expands to enclose its members, placing a shared card between the two clusters makes the frames overlap naturally.
- Prefer an outline over a fill — Filling a frame hides the overlap under whichever group’s color is in front. Changing only the border color keeps the overlap readable.
- Keep it to about three overlapping sets — Four or more makes the overlaps too complex and actually harder to read.
The Venn diagram was introduced by the British logician John Venn in 1880. Wikipedia