The next morning I sit in a tree and watch as the yellow school buses leave one after the other.

And, because I’m such a good thinker, I think: Why are the buses called yellow? They are definitely not the color of daffodils or dandelions or forsythia blossoms or any other yellow flowers I can think of. The closest I can come to that color is marigolds, which can be yellow or orange, and if you look at a patch of them all together and squint your eyes, that’s the color of school buses. So why aren’t buses called something-sort-of-but-not-exactly-like-marigolds?

My honorary cousins the geckos like to be accurate about everything they say—they tell me that’s the scientific way. I resolve to be more scientific, too. From now on, I will call buses something-sort-of-but-not-exactly-like-marigolds-colored, and I will encourage others to be accurate that way also.

I’m so busy thinking these deep thoughts, I almost don’t notice that all of the buses except for one have left. The geckos told me that this was what would happen, and that the one remaining bus would be the field trip bus. The children have gone from all of their various buses into the school to be counted, and soon they will come out and board this one bus to ride to the museum and science center that’s named after my cousin the gecko.

One thing that both my gecko cousins agreed on is that I must not be seen getting on the bus, even though I explained to them that everybody loves squirrels, and that I would be welcomed. But they told me that—loved or not—nobody is allowed on the buses besides the driver and the children. A special exception is made for field trips, when select parents and teachers will be named as chaperones. Chaperones are those in charge of keeping the children from wandering off and getting lost, since people children do not stick close to the nest, the way well-behaved squirrel children do.

I will trust that the geckos are right when they say I should not let myself get seen.

They also advised against simply climbing to the top of the bus and riding there. They talked about crosswinds and wind blasts and wind shears and wind gusts, not to mention lift and drag and aerodynamics, until my head was ready to wibble-wobble right off my shoulders.

“No riding on top,” I promised them.

So now I’m watching the bus driver, who is sitting in his seat and has the bus door open. He’s reading a book and probably would not notice me going up the same stairs the children do, because people tend to not notice quite a bit of what goes on around them.

But several of the windows are open, so I decide it’s just as easy to go in that way.

I jump from the branch that’s closest to the bus (I’m an excellent jumper) and land on the roof of the bus (I’m an excellent lander). From here I can see into the window of the room in the school where the geckos live. I stand up and wave at them. They must think I have not listened to their advice and plan to ride here, because I see one of them lift his little foot with its tiny padded toes—not to wave back, but to clap against his forehead.

So that they won’t worry, I don’t linger but go to the edge of the roof of the bus. Holding on to the edge, I swing down and in through the open window.

I land on one of the seats.

The bus has many seats, and they all face toward the front. That’s the same arrangement as in the classrooms in the school, except that in the classrooms, the teacher faces the children, and on the bus, the driver faces away from them. I stand on the seat where I’ve landed and look where everyone will be facing. It is just another window. If they want to see outside, they should go outside, where they’d have a clearer view.

The driver puts down his book, but not because he’s seen me. He’s seen the children who are to go on the field trip, who are bursting out of the front door of the school. The geckos were certainly right that the children seem excited about their field trip. They are talking and laughing and running—even though the teacher chaperones call out, “Walk!”

One of the children is neither running nor walking. He is riding in a metal chair with two big wheels in back and two small wheels in front. I have seen this child before. Sometimes he turns the big wheels with his hands to make his chair roll; other times one of the teachers pushes his chair to make it go. I have heard other children offer to push the chair, but the teacher always says no because they will push it too fast. I have seen the boy go pretty fast on his own.

The driver and the teacher work to get the chair onto the bus, which gives me a little time, but not enough to explore the bus or to search out the perfect hiding place. So I simply jump down to the floor and hide under one of the seats.

Stomp! Stomp! Stomp! The children’s feet make the floor shake, but I know nobody can step on me where I am.

Oops! I realize maybe I’m not as safe as I thought as a boy throws himself into the seat where I was and swings his feet to where I am. I dodge, moving closer to the wall of the bus.

“The sooner you find seats, the sooner we can get going,” the adult people tell the people children.

It would be hard for the children not to find seats, since the bus is made up almost entirely of seats.

Still laughing and talking and stomping, the children find seats.

There’s a loud noise as the bus starts. I’ve heard buses start before, but it sounds louder from the inside.

And the children sound even louder than they do on the playground at recess.

Probably the geckos have a scientific reason for this to be so.

Then the bus moves, and I unexpectedly find myself sliding backward. I look up and I’m no longer seeing the bottom of the seat under which I was hiding. I’m seeing the boy with the big feet. Luckily, he’s too busy poking the boy next to him and neither one of them sees me.

I scramble back to under the seat ahead of the two boys and dig my nails into the floor.

But every time the bus stops or starts or turns a corner, I have to fight to hold on. Having to hold on is like when I play on the squirrel playgrounds people put in their yards around the food they set out for us. There are slides and swings and sometimes it’s a real challenge to get to the actual squirrel feeder with its yummy snacks.

I wonder if this is what the geckos meant by aerodynamics.

Speaking of snacks, something besides me that is sliding around on the floor is half a peanut butter sandwich. I wonder if one of the children has seen me and is sharing, or if the sandwich got left behind by accident. People can be careless with their food that way. In any case, offered or forgotten, I munch the sandwich, between sliding and holding on.

Finally the bus stops. I have been concentrating on not sliding backward or to the sides, but this time I slide forward. I slide between a pair of pink sparkly sneakers and the only thing that stops me from sliding forward even more is a pink sparkly bag—the kind people call a backpack.

I scramble back before the girl who owns the pink sparkly sneakers and backpack can see me.

The driver calls out to everyone, “It looks like rain, so close the windows. I’ll be parked here. Here is where you come back to at two fifteen. Have a good time.”

Yikes! If the windows are closed, how will I get off the bus without being seen? I don’t want to have come all this way just to wait on the bus while all the children get to see the Galileo Museum and Science Center.

And the most bothersome thing of all is: the bus driver is wrong. One good sniff of the air, and I can tell that it’s not going to rain until evening. That bus driver’s nose doesn’t work properly.

I look at the pink sparkly backpack that stopped my slide. I can tell by the way the pink sparkly sneakers are planted firmly on the floor facing sideways that the girl who is wearing them is busy closing the bus window nearest her.

The backpack has a buckle and a zipper. The girl hasn’t buckled the buckle or zipped the zipper. There’s no time to search out a better choice, so I dive into the backpack.

There’s a notebook and some pencils and an apple in here. An apple! How thoughtful of the girl! I always have room in my tummy for an apple. I think better of the girl even though her backpack is decorated with a picture of a kitten wearing a pink sparkly dress, which makes me very nervous. I hope the girl doesn’t think it’s a good idea to put a squirrel into a sparkly dress.

But before I can have second thoughts, I feel the girl lift the backpack and start walking.

One of the teachers claps her hands in that way that means Please be quiet and listen. “Children,” she says, “I know you will be on your best behavior anyway, but I wanted to warn you that the museum was considering canceling all the field trips today because they have been having trouble with thefts. Please be aware that—because of this problem—they will be inspecting all backpacks and bags before we leave.”

If inspecting means what I think it means, I’ll have to find a different way to leave the museum than the way I am getting in.

But meanwhile we are leaving the sort-of-but-not-exactly-like-marigolds-colored bus and going into the museum and science center.

All I can do is start munching that apple.