The episode starts out with the family in the kitchen discussing their summer plans. Edwin is going to business camp, Lizzie is going to soccer camp, and Marti are going to camp at the highschool, where Casey will be the counselor. (There is also a moment in which Lizzie refers to George as "Dad" which was just weird) Casey begins to give out business cards, for whatever reason, when Derek walks in. Casey comments that he should be at the beach working as a bikini inspector (he looks awful, like he just woke up) and he begins repeatedly grunting at the talk of him going to summer school to retake a Physics exam. He continues to grunt as Casey smiles and laughs and hands him one of her cards and says that she'll "see him at the water fountain."
After the beginning credits, we find out that George mixed up the date for Edwin's camp, so he will have nothing to do for this week. Then Lizzie and Nora walk in and inform them that Lizzie's camp was cancelled due to lice, so she will be free this week as well. We also find out that Derek is the only one in his summer school class, because he's the only one that failed the final. (To spend summer at the school with Casey, maybe? ) Casey and Marti are also shown at their camp. Casey meets the kids and tries to get them excited for fun, education activities, but they aren't interested. Ashley's performance during these scenes is pretty entertaining because Casey is so into the activities, one being building a hospital out of popsicle sticks, but that's later in the episode.
Then, since Liz and Edwin are home with little to do, Edwin thinks up an idea after seeing that Lizzie is pet-sitting. They then start a business of taking care of people's pets. The house becomes filled with lizards and other caged animals and the rest of the house gets pretty upset about them being everywhere. This storyline of them taking care of the pets continues on for the rest of the episode, and there's a couple of bonding scenes between them.
On the Derek and Casey side of the episode, they both return home that day and are upset with how the summer is going. Derek has to study, Casey gets painted by the kids. The next day, Derek's teacher says that he is leaving to play golf since Derek really isn't making much of an effort, however Derek has to stay in the school. While Casey is getting excited about building that hospital out of popsicle sticks, Derek goes by the door on his skateboard and Marti sees him. She asks to go to the bathroom and whispers to the other kids to sneak out, which they do when Casey isn't looking. When she sees that they're gone, she goes looking for them and hears a scream. She goes to a classroom and is soon bombarded by paper balls and learns that Derek and the kids are behind it. When they go back home later, Casey and Derek decide to work together at the camp since he's in school anyway and she's in over her head, but only if he gets half of her pay. The next day Derek plans this alien/spaceman obstacle course for the kids to do. You can really tell how good Derek is with kids in this scene. (I bet Casey could too I can't see Sam or Max doing everything that Derek did for the kids) Anyway, since the kids clearly like Derek better than Casey, she gets upset and sits in the corner watching them have fun. Marti sees this and tries to cheer her up, asking if she wants to go on the obstacle course. Casey says no because it "isn't her thing" and Marti tries to cheer her up again by saying that Casey is pretty, smart, and organized, and that she likes spending time with her. Marti then asks her again, but Casey refuses again. This time Derek comes over with a hula hoop and puts it around Casey and says "forcefield activated" (it's part of the course) and they smile and look at each other for a second before Casey turns to Marti and grins. (This is seriously my favorite moment of the episode. There's just something about it... it's one of the best Dasey moments, imo, even though it's only a few seconds long.) Casey then joins in on the course and clearly has a lot of fun. When the kids leave, they address Derek and Casey as "captain" and "lieutenant" which I thought was cute. Then Casey thanks him for "unleashing the kids' inner troopers" and her's. She also says that he can use any of her Physics notes. That's when Derek realizes that he has to take the test tomorrow.
When they get back home, Casey goes in his room to see how the studying is going. He says that he doesn't understand it, so Casey and Marti do a little poem with some of the Physics laws to help him. He acts like he doesn't need it, but when Casey peers in after he whispers the poem to himself and she smiles. It then cuts to Casey and the kids waiting outside the classroom to see if Derek passed. When he comes out, Casey asks if he did but he says the teacher is still grading it. Then, the teacher comes out and Casey asks him if Derek passed. He replies that Derek got a 51 and Marti asks if that's good. The teacher says "no, but-" and Casey and Derek cut him off saying it's passing. They also do this little high five thing... it's so cute. After that all the kids cheer and Casey says "the kids and I are wondering if... you'll come back to camp with us." The kids begin to chant "one more week" and Casey looks up and smiles at him and also says "one more week." He agrees, saying it's because he's good with kids. He picks up Marti and Casey gazes and smiles at him.

This episode is so cute. I mean, Derek and Casey get along... and take care of kids together! It's like "Misadventures in Babysitting" but better. (By that I mean that they take care of the kids, there's nothing with Max or anything )