Card sorting in workshops: how to collect and cluster ideas

Card sorting is a facilitation method where everyone writes their ideas down individually, one idea per note, and the group then arranges them into themes on the wall. In a short time it shows what the whole group thinks, not just what the loudest people say.

In open discussions, the same three people often do the talking while the rest stay quiet. In card sorting, everyone writes at the same time and in silence. Every idea ends up visible on the wall, and every idea counts the same, no matter who it came from.

Some know it as the Metaplan technique or, in German, the Kartenabfrage. The sorting step at the end is often called affinity mapping.

What is card sorting?

The method grew out of the facilitation techniques developed in Germany in the 1970s. The core is simple: first everyone writes on their own, then the group sorts together, and only at the very end does anyone evaluate.

That separation is what makes it work. Writing alone first means nobody gets steered by the first loud opinion in the room. And because notes usually go up without names, the idea counts rather than the person behind it.

Here, the aim is less to debate and more to make things visible. The discussion comes later, and then it is based on everything the group actually thinks.

What you need for card sorting

• Electrostatic notes for the ideas, one idea per note
  • Larger notes for the cluster headings
  • Small notes as dots for the vote at the end
• Permanent markers with a thick tip, so every note stays readable from a few meters away
• A smooth surface: a whiteboard, window, door, or foldable whiteboard
• 45 to 60 minutes, depending on the size of the group

Electrostatic notes have a clear advantage here: during clustering they move back and forth several times, and you can slide them across the surface without peeling them off and sticking them again. There is more on how they work in our post on static sticky notes.

Card sorting, step by step

1. Write the question (5 minutes): Put an open, specific question on the wall where everyone can see it. The more precise the question, the more useful the answers. "What can we do better?" is too broad. "What stops us from finishing projects on time?" works.

2. Write individually (5 to 10 minutes): Everyone writes in silence, one idea per note, in block capitals and no more than three lines. Avoid having two ideas in one note as they cannot be sorted separately later. Stattys Notes S and Stattys Square are exactly the right size for this.

3. Collect and read aloud (10 minutes): The facilitator collects the notes, reads each one aloud, and puts it on the wall. Questions for understanding are allowed, judgements are not, at least not yet. This way the whole group hears every idea once, including the quiet ones.

4. Cluster (10 to 15 minutes): Now the group sorts together what belongs together. Similar notes move next to each other, duplicates go on top of one another. Let the group do the sorting rather than the facilitator alone, because the shared understanding forms during exactly this step.  

5. Name the clusters (5 minutes): Give each cluster a heading on a larger note, such as Stattys Notes M. A good heading sums up the cluster in a few words, and that is also the test of whether it really belongs together.

6. Prioritize (5 minutes): Everyone gets three dots and places them on the clusters that matter most to them. Stattys Notes XS work well as dots, because they can be moved again if someone changes their mind. Afterwards it is clear where the group wants to start.

7. Agree next steps (10 minutes): Turn the two or three strongest clusters into concrete actions: what happens, who takes care of it, and by when? Without this step, even the best wall stays a snapshot.

What a session can look like

A team of twelve notices that decisions take too long. The question on the wall reads: "Why do our decisions take so long?"

In eight minutes, around 40 notes go up. Reading them aloud shows quickly that many people mean the same thing in different words. After clustering, four themes remain:

• Too many people involved
• Unclear who makes the final call
• Missing preparation before meetings
• Too many rounds of alignment

In the vote, most dots land on "Unclear who makes the final call". The team agrees that from now on, one person is named as responsible for each topic before the first meeting. The whole session takes just under an hour.

Outside of work, too

Card sorting works anywhere a group needs to work something out together, not only in the office.

A church community planning its youth work for the coming year might ask: "What would you like from the youth group?" The young people write for themselves, instead of adults talking about them. In groups where not everyone dares to speak up, that makes a real difference.

The same method works just as well in a classroom, a club, or a parents' evening.

Common mistakes

• The question is too broad. Answers cover everything, and nothing can be sorted in a useful way.
• People discuss while writing. That holds back the quiet ones before they have noted anything down.
• Several ideas share one note. They cannot be placed separately afterwards.
• The facilitator clusters alone. In the end, only one person understands why the wall looks the way it does.
• Evaluation starts too early. Commenting while notes are read aloud takes away the courage of others to show theirs.

What if part of the group is remote?

Card sorting relies on the wall in the room. If a few people join online, they post their ideas in the chat and someone in the room writes them onto notes on the wall. A photo of the wall after each step keeps everyone on the same page. If the whole group is remote, a digital whiteboard is the better choice.

Materials for your next session

Stattys Notes S (10 x 7 cm) – Electrostatic Notes for Planning & Sorting

The classic size for collecting ideas. One idea fits comfortably, and the note is still readable across the room. If you run card sorting regularly, this is the size to keep in stock.

Stattys Square (7.2 x 7.2 cm) – Electrostatic Notes for Clustering & Prioritizing

Just as good for collecting ideas. The square format lines up in clean rows and columns, and it is slightly smaller than S, so more ideas fit onto one board.

Stattys Notes M (20 × 10 cm) – Electrostatic Notes for Bigger Ideas & Plans

Best for the clustering step. Write each cluster's heading on an M note and place it above the notes that belong to it. At 20 × 10 cm it stays readable from across the room, so everyone can follow how the wall is organized.

Frequently asked questions

How many people does card sorting work for? It works well with five to twenty people. With larger groups, split into smaller rounds and bring the results together afterwards.

How long does it take? Depending on the size of the group, 45 to 60 minutes. The timing for each step is listed above.

Do people write their names on the notes? Usually not. Without names, the idea counts rather than the person, and critical points are more likely to come up.

What is the difference between card sorting and brainstorming? In classic brainstorming, people call out ideas to the group. In card sorting, everyone writes on their own first. That way the thoughts of the quieter people make it onto the wall too.

Which pens work best? Permanent markers with a thick tip. They stay readable from a distance and do not damage the notes.