When Marty and Courtney are figuring out the division of duties, they used a Venn diagram to list some duties. But they didn't do so correctly. One circle is Courtney's duties ("pumping") and one is Marty's ("bottle prep"), with "diapers" as a task shared between them. But there's a third circle as if there's a third person who has duties, but it just says "Baby gets hungry", which is an event, not someone to share the work or a task. Then the shared space between all 3 - which should be a task everyone shares - just says the desired result: "Happy Baby". As scientists they would both understand the usage of Venn diagrams better than this.