Proof Rummy
Purpose:
Increase student enthusiasm about proofs. Develop student reasoning skills in planning out two-column/flow proofs.
Materials:


Notecards (at least two packs)
One five to seven step proof


Timer (wall clock)
Markers
Set up (15-20 minutes): Ideally, students should be separated into groups of three or four (however, this activity may be
done individually after students have acquired some familiarity with it). During set up time this is when you would
introduce the proof you are building your rummy deck from to your students (you can have them derive it on their own,
with your help, etc. depending upon the level of the class). For the sake of an example, I will use the Isosceles Triangle
Theorem.
After students have been introduced to this proof they count out notecards to copy it onto. Each group needs
(two times the number of steps of the proof) notecards, so for the Isosceles Triangle Theorem I would distribute
twelve notecards to each group. Each group will write each statement and reason on separate notecards with a
sharpie or marker (make sure all groups are using the same color marker). When all groups finish, collect their
notecards and shuffle them all together.
Proof Rummy (10-15 minutes per game) –
1. After shuffling your proof rummy deck, evenly distribute proof rummy cards to each group face down
(no peeking!)
2. After each group has their cards give them one minute of think-time to organize their hands. The goal of
the game is to complete the proof from the rummy cards before every other group.
3. After think-time each group passes a card they don’t need to the next group at the same time. This
should be an instantaneous pass.
4. Every five seconds yell, “Pass!”, and each group will pass a card they don’t need to the next group. Each
group should always have the same number of cards they started with.
5. The first group that shouts rummy and has a correct proof of the theorem wins the game.
Side notes:
For lower-level Geometry classes this is a great activity to get the students excited about proofs. There’s also a
lot of kinesthetic activity involved since students are constantly passing cards to other groups. You may need to
start passes of at 10 seconds between each pass to help these students get used to the activity. It is extremely
important that all passes occur at the same time.
For more advanced-level students consider trying this activity out on an individual basis where students
compete, independently, with one another in their own groups, so that there are several separate games going
on at the same time. You can even assign several different proofs in a game so that students are not all solving
the same proof in a game (however, make sure your proofs you are using have the same number of steps).
Examples of notecards for Isosceles Triangle Theorem:
̅̅̅̅
𝑨𝑪 ≅ ̅̅̅̅
𝑩𝑪
Given
̅̅̅̅ bisecting < 𝑨𝑪𝑩
Draw 𝑪𝑫
Angles have unique bisectors
< 𝟏 ≅< 𝟐
Definition of angle bisector
̅̅̅̅ ≅ 𝑪𝑫
̅̅̅̅
𝑪𝑫
Reflexive Property of Congruence
∆𝑨𝑪𝑫 ≅ ∆𝑩𝑪𝑫
SAS
< 𝑨 ≅< 𝑩
Corresponding angles of congruent
triangles are congruent