They say you can’t teach an old dog new tricks.

What they didn’t say is that an old dog can teach itself new tricks.

In my Montessori Physical Education Volume II, I had a lesson on hybrid plants that I thought could be improved. It didn’t fully explain why some things inherit certain traits and others did not. When I looked back at the lesson to figure out how to more gracefully explain this concept, I went down a rabbit hole that led me to Punnett Squares. I had heard of these before, but didn’t truly understand what they were. After hours of reading and experimenting, I taught myself the basics of Punnett Squares. I soon realized how I could completely overhaul the old hybrid plants lesson into one that teaches Punnett Squares.

Here is the much better lesson on inherited traits. While this lesson is technically untested, I am very excited to try it with my middle school students this year!

Punnett Squares

Montessori Physical Education

 Introduction:

Students commonly learn the parts of a seed and parts of a flower for their botany studies.  However, we see variety in those parts. Why does this happen? This game can serve as an extension of those lessons by looking at the concept of genetic traits in plant hybrids for our lower elementary students. When two plants of the same species are planted together to promote cross-pollination, the hope of the planter is that a hybrid plant will be created that has the traits that the planter is looking for. Typical reasons for cross-pollination include better tasting fruit, earlier maturation, less care and water is needed, and disease resistance.

Punnett squares are diagrams that are used to predict expressed genotypes from breeding organisms. This diagram is the visualized work for Mendel, whose work is the foundation for the modern study of genetics. This lesson plan contains a lower elementary version and upper elementary version that will help explain how these diagrams are used through games. The students will represent the offspring inheriting the different genotypes, which dictates how they are able to play the game.  This will provide a fun, concrete experience for your students to see how Punnett Squares help predict how traits are passed on from generation to generation.

Materials: 

·      A large open space (such as a gym or field)

o   If played in a gym, if you have access to adjustable basketball hoops, that works perfectly.

o   If playing outside, large 55-gallon waste containers and hula-hoops (with holders that hold them vertically)

·      Soft dodgeball or throwing ball for lower elementary

·      Basketball for upper elementary

·      Hula hoops

·      Colored jerseys

·      Whiteboard and dry erase marker

Minimum Amount of Students Needed:

For the lower elementary game, you would want at least eight students. For the upper elementary game, you would want as close to sixteen as possible.

Prior Knowledge: For lower elementary, the students should have had the lesson on parts of flower and parts of a seed. For upper elementary and middle school students, it would be nice if they have begun their studies of genetics.

Lower elementary presentation 

·      Explain to the students that they are going to be playing a game that has the basic game mechanics of a game called ultimate Frisbee.

o   Each team is trying to get their ball into the net or through the hula-hoop (depending on which version of the game you are playing).

o   When a player has the ball, they are only allowed to pivot on one foot. If they take more than one step, it is a turnover, and the ball goes to the other team. Players are free to move and run as they please without the ball.

o   Someone guarding the thrower must give them space so they can pivot and throw. 

§  To enforce this “halo rule,” if the throwing player can tag the guarding player with the ball, the defender must sit down until the ball has been thrown.

§  There is a five second time limit that someone can hold the ball. If they hold it longer than that, it is a turnover, and they must give the ball to the other team.

o   When a pass is made and is not caught, it is a turnover to the other team. If a defensive player deflects a pass and it hits the ground, it still is the defender’s ball because they stopped the pass.

o   When the turnover happens, a member from the defending team picks up the ball from where it hit the ground and they are now on offense. The player who starts with the ball cannot move from that spot until they throw the ball. 

§  The best play a defender can do is intercept the ball because they can immediately begin passing it to a teammate on offense.

·      Once the rules of the game are explained to the students, we need to find out how they are allowed to shoot and pass, which will be based on their Punnett Square placement.

o   Create a simple Punnett Square with a dominant O and a recessive u.

§  The dominant O is the trait for Overhand throwing and shooting.

§  The recessive u is for underhand throwing and shooting.

o   Place the students names evenly in the four squares. Show them what trait they inherited from their “parents.”

In this version, both parents are overhand dominant and underhand recessive. We see that the offspring have a 75% chance of being overhand throwers, and 25% chance of being a underhand thrower.

You could also use a version where one parent is overhand dominant and underhand recessive, and the other parent is double underhand recessive. This makes it a 50/50 chance that the offspring will be an overhand thrower or an underhand thrower.

·      In one version of the game, use basketball hoops (or 55-gallon containers if outside) as the target for the students to shoot the ball into. This will make it easier for the students who shoot underhand to score a goal because the mouth of the goal is horizontal.

·      Play the game again, but this time put a hula-hoop around the rim (or use the hula-hoop holders if outside). The hula-hoop is now the target. This will make it easier for the overhand throwers to score, while the underhand throwers will have to get much closer to the hoop to be able to score accurately.

·      Having two different types of games symbolizes different environments that the offspring plants are trying to grow in. An advantage in one game (environment) may not be an advantage in another game (environment).  

Upper elementary and middle school presentation 

·      Explain to the students that they are going to play a game that has the basic game mechanics of basketball.

o   Split the students into two even teams.

o   Each team is trying to get the ball in the basket. Any shot inside the arc is worth two points, and a shot outside the arc is worth three points.

§  If there is a foul that requires free throws, give the player one free throw worth two points. This will keep the pace of the game fast and keep the shooting rules consistent.

·      A player with a dominant P is allowed to pass the ball, but they cannot dribble. A player with a recessive p is allowed to dribble, but they cannot pass.

·      A player with a dominant S can shoot anywhere inside the arc worth two points. A player with a recessive s can only shoot outside the arc three points.

o   If this player gets fouled, they must take their free throw outside the three point line which is worth three points.

·      All the other rules of basketball apply.

·      As evenly as possible, have the students put their names in an empty 4x4 grid, or place them yourself. Once the names are placed, reveal the traits of their “parents.”

o   Pass (P)       

o   Dribble (p)

o   Close Shot (S)

o   Three Pointer (s)

For this game, both parents are going to dominant P (pass), recessive p (dribble), dominant S (close shot), and recessive s (three pointer shot). That would look like “PpSs.” Since there are two parents, we need to make each combination of dominant and recessive pairings within our Punnett Square.

Here is an example of the Punnett Square with associated traits.

o   Once the students know their trait combinations, we can play a game of basketball! The students will enjoy playing within the limitations of their imposed traits, and deciding what strategies they should use to maximize their potential.

 Aims:

Direct:    For the students to learn how Punnett Squares work in predicting inherited traits.

Indirect: 

 Listening to directions

Teamwork and team building

Strategy

Communication

Determination and grit

 Physical skills practiced: 

·      Throwing the ball into a container or shooting a basketball into a basketball hoop

·      Passing and catching a ball

Control Of Error: 

The instructor will have to use a white board to record the students and what their traits are. The instructor will also have to act as the referee for the games.

Points of Interest:

The students will enjoy playing within the limitations they have imposed on their traits, and what strategies they should use to maximize what they can do.

Age: All Ages