• 13 parts
  • Checked October 2026

Blood Typing Cards

Three wells on a card, clumped or smooth: read them and name the blood type.

Blood Typing Cards

Name Date

Tap any part to read, rename or leave it out

1 2 3 4 5 6 7 8 9 10 11 12 13
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Write the name of each numbered part.Answer key

  1. Anti-A well
  2. Anti-B well
  3. Anti-D (Rh) well
  4. Clumped well (agglutination)
  5. Smooth well (no agglutination)
  6. O negative
  7. AB positive
  8. A positive
  9. B positive
  10. O positive
  11. A negative
  12. B negative
  13. AB negative

Own chart from plain geometry, 2026-10-03. Licence: own work.

Each numbered ring is a button. Use the arrow keys to move between them and Enter to choose. Names are read out in Study, and once a part is answered.

Next step Next: the antigens behind each blood type

All 13 parts on the diagram

Show the list

One card 5

  1. Anti-A well This well holds anti-A serum. It clumps red cells that carry the A antigen.
  2. Anti-B well This well holds anti-B serum. It clumps red cells that carry the B antigen.
  3. Anti-D (Rh) well This well holds anti-D serum. It clumps red cells that carry the Rh factor, the D antigen.
  4. Clumped well (agglutination) The red cells have stuck together in clumps. The serum in this well met its antigen.
  5. Smooth well (no agglutination) The blood has stayed smooth and even. The serum in this well found no antigen to bind.

Eight cards 8

  1. O negative No well on this card clumps. The red cells carry no A, B or D antigen.
  2. AB positive All three wells clump. The red cells carry the A, B and D antigens.
  3. A positive The A well and the D well clump. The red cells carry the A antigen and the Rh factor.
  4. B positive The B well and the D well clump. The red cells carry the B antigen and the Rh factor.
  5. O positive Only the D well clumps. The red cells carry the Rh factor and no A or B antigen.
  6. A negative Only the A well clumps. The red cells carry the A antigen and no Rh factor.
  7. B negative Only the B well clumps. The red cells carry the B antigen and no Rh factor.
  8. AB negative The A well and the B well clump. With no Rh factor, the D well stays smooth.

How this list was compiled: Every statement checked on 2026-10-03 in at least two of these. (1) Wikipedia, text only: Blood compatibility testing, Hemagglutination, Agglutination (biology), ABO blood group system and Blood type, https://en.wikipedia.org/wiki/Blood_compatibility_testing (anti-A, anti-B and anti-D reagents, called antisera; agglutination is red cells clumping together; the card method). (2) NHS, Blood groups, https://www.nhs.uk/conditions/blood-groups/ (the antigens of each group; red cells mixed with antibody solutions clump when they carry the matching antigen; eight groups with RhD). (3) MedlinePlus, US National Library of Medicine, Blood typing, https://medlineplus.gov/ency/article/003345.htm (blood mixed with antibodies to types A and B, checked for cells sticking together; Rh typing done the same way). (4) A lab test reference, Blood typing, https://www.testing.com/tests/blood-typing/ (anti-A and anti-B serums, anti-D serum for Rh typing, clumping). (5) A card maker's own page, https://www.eldoncard.com/ (a card with circles of antibody reagents that agglutinate with the matching antigens). The drawing is our own. Licence: own work

The drawing: Own chart from plain geometry, 2026-10-03; nothing traced. The eight cards are drawn by a script from the answer table in this dataset. Licence: own work

How it works

A blood typing card has a well for each test serum: anti-A, anti-B and anti-D. Blood clumps in a well when its red cells carry that antigen. The second chart has a card for each of the eight blood types.

Read the full guide

Clumped or smooth

The well marked A holds anti-A serum, B holds anti-B, and D holds anti-D, the serum for the Rh factor. When blood is mixed in, the antibodies in a serum bind red cells that carry the matching antigen, and the cells gather in clumps. That is agglutination. With no matching antigen the blood stays smooth.

Naming the type

Clumps in the A well alone mean type A, in the B well alone type B, in both AB, in neither O. A clumped D well makes the type positive; a smooth one makes it negative.

  • Read A and B first for the letter, then D for positive or negative.

Questions and answers

How do you read a blood typing card?

Look at each well. A clumped well means the red cells carry the antigen that well tests for: A, B or D. A smooth well means they do not. The clumped wells together give the blood type.

What does agglutination mean in blood typing?

Agglutination is red blood cells clumping together. It happens when antibodies in the test serum bind a matching antigen on the cells. Where the cells carry no matching antigen, the blood does not clump.

What do anti-A, anti-B and anti-D test for?

Each is a serum of antibodies against one antigen. Anti-A clumps red cells that carry the A antigen, anti-B clumps cells with the B antigen, and anti-D clumps cells with the Rh factor, also called the D antigen.

Which blood type shows no clumping on the card?

O negative. Its red cells carry no A, B or D antigen, so every well stays smooth. AB positive is the opposite: its cells carry all three antigens and all three wells clump.

How do I label the blood types on the cards?

Read the A and B wells for the letter: one clumped well names it, both mean AB, neither means O. Then the D well: clumped is positive, smooth is negative. These cards are our own drawing, made for practice.

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