Bella doesn't understand the math, but she's fascinated by the magic. "How far can you go from where the person whose memory it is is?"
"Can you see farther than that? Can you see things the person didn't know were there even at the time, like somebody hiding? Can you look behind and under stuff? When you walk around are you your same size in the memory?"
And she is standing in this very room, just behind the past Maria, watching her begin to write those equations on the board. The whole scene has a kind of ghostly, unreal quality, but wherever she turns her attention, individual details are sharp and clear.
Bella inspects the contents of the room. She tries touching things.
That's interesting. She tries sticking her head through a desk drawer to see if she can inspect its contents.
Of course. She pulls her head out and goes on checking out the way the memory works; she tries holding her hand still in the path of Mrs. Stark's moving elbow.
She starts looking behind things, and at things that would not have gotten Mrs. Stark's attention - dust motes swirling in the light, objects under the desk.
Interesting. Is there an open door? She wants to test the boundaries of the memory.
If she takes another step, things get misty around the edges.
Another step after that, and when she looks down the stairwell, everything is blurred and silvery; the door behind her, and a bit of the wall around it, is the only clear and solid thing remaining.
That remains the case for an unknown length of time.
Then the whirling sensation from before fades in slowly, and she is flung out of the memory to land on her feet with considerable backward momentum.
"I'm not very graceful. I'm okay flying," says Bella. "Just not on the ground." She hauls herself up. "That's really cool. Are they expensive?"