(SciGirls) There's paint on the floor, and footprints, and there's glitter over here.

(Lindsey) The reason that we're looking at this cabin for evidence is due to a scientific principle called Locard's Exchange Principle.

It simply means that when 2 things come in contact with each other, they transfer part of each other onto the other.

Whenever you touch something, you always leave a trace behind, and that thing leaves a trace on you.

We're going to walk around the room, take a very careful look.

There's a certain path we have to take as we walk around the room, so we don't mess any of the evidence up.

You've got spilled paint you guys noticed before, there's also shoe prints here.

(Christina) They must have knocked it over as they were hurrying out of the room.It looks that way.

And there's also a notebook that has a page ripped out.

(Lindsey) Yes, the page is ripped out of the notebook, it's important to note how things are in the original state you find them in.

So now we have two things missing from the cabin-- the note and the mask.

Lindsey shows us to collect anything that might be relevant in the crime.

She said that anything that might have been disturbed or like, shouldn't normally be there is something we should collect.

(Lindsey) This is the case where the mask was kept.

And you're going to want to note the door being open almost all the way, (Emi) It looks like there's more glitter inside.

We did a walkthrough; Christina's job was taking pictures of everything she saw and processing the crime.

My job was taking notes of everything I found.

Emi's job was to take measurements of the crime scene, and make sure that we could make a floor plan.

After documenting the evidence that we saw, we started collecting and numbering the evidence that we found.

The glitter on the floor in front of the door is item number one.

(Emi) We put up cards to note where all the evidence was.

Then we took pictures of each piece of evidence with its card.

(Lindsey) Collecting glitter, because it's small, best thing to pick it up with.

Lindsey showed us different ways to collect evidence, like a really unique and cool way that she taught us was to collect glitter from the floor by using a sticky note and sticking it actually on the glitter, and then folding it over itself then packaging up the evidence.

I'm gonna have you guys place the rest of the tents and we'll collect that evidence together.

♫♫ (Christina) Number 2 is the notebook paper.

Number 3 would be the smaller footprints.

We collected the notebook on the desk.

We actually cut out the footprints and the paint on the paper on the floor.

And we also collected 3 samples of glitter.

There was some on the floor, there was some in the front of the mask case on the table, and actually some inside the mask case.

When we put our evidence into the paper bags, we had to make sure that they were completely sealed so nobody could tamper with them.