Cameras are everywhere these days. In phones, computers, tablets, and sometimes even all alone by themselves. In the modern age most cameras are digital, which means they store pictures using electronic memory like computers. In the not-too-distant past, cameras used materials that were photosensitive, which means that they change when light is shined on them. Light from the outside world would shine on the photosensitive materials and leave an image on it.

Back before anyone invented photosensitive materials, though, people were still experimenting with ways of capturing an image of the world with a box they could look through. The camera obscura (Latin for “dark chamber”) is one of the ways they did this, and humans have been building camera obscuras for thousands of years, since ancient Greece.  Some are so big you can sit inside! (This one is in New York).

Today you’re going to follow in that grand tradition and build your own camera obscura that will allow you to see the world in a very different way!

You’ll need:
A piece of deli paper
A toothpick
Black electrical tape
A push pin
Painters tape or other tape
An empty cereal box or other, similarly shaped box
A pencil or pen
Good scissors

(1) Using your scissors, cut all the way around the cereal box a few inches above the bottom. You want your cut to be as straight as possible. When you are finished, the cereal box should be in two pieces: the short bottom section and the rest of the box.

(2) Trace the box bottom on the piece of deli paper and carefully cut out the tracing.

(3) Using your tape, attach the paper rectangle to the box bottom. Fold any extra paper over the sides of the box and tape it down. Make sure the paper is as smooth and flat as possible by pulling all four sides nice and tight as you tape them down.

(4) Using the electrical tape, tape the bottom of the cereal box back into position, so that the paper you just attached is sandwiched between the two pieces.  Electrical tape is opaque, which means light can’t get through it and into your camera obscura.

(5) Cut an eye hole out of one of the top flaps on the box.  Then use the electrical tape to tape the top closed.
NOTE: We recommend putting your eye hole in the middle – where the “ee” in the Cheerios box is located, not over to one side like we’ve done in this box.

(6) Tape all the seams on the bottom of the box so light can’t get through them.  Then use your pin to poke a hole right in the center of the bottom of the box.  If you look close, you can see the head of a pin in the middle of one of the “e’s” in the picture below.

(7) Use your toothpick to make the hole a bit bigger.  This hole lets the light into the box.  The light will shine on the rectangle of paper and will project an image of whatever the box is aimed at.

(8) Go outside. Point the bottom of the box at something well lit by sunshine.  Look through the eye hole on the top of the box.

HINTS:
You may need to use one hand to shade your eyes from the sunshine.
You will need to give your eyes a few moments to adjust to the dim light inside the box.
Things with a lot of contrast work best – like a tree with the sky behind it.

What do you see on the paper inside the box?  What’s weird about what you see?  Why do you think that is happening?

What to know more?  Read on!

Did you notice anything weird when you were looking through your camera obscura? Maybe you noticed that everything you look at looks upside-down? It’s pretty strange!

This happens because of the way the light moves through the pinhole. You’re looking at objects that are way bigger than the pinhole. The light coming off of them only travels in straight lines, so when the light from the top of the object goes through the pinhole, it’s moving down towards it. It keeps going down and ends up on the bottom of your paper screen. The opposite is true of the light from the bottom of the object: it moves up to the pinhole and ends up on the top of your paper! Think of it like spraying a garden hose through a little hole in the fence. If you spray from above the hole, the water will shoot down out the other side, and if you spray from under the hole it will shoot up when it comes out.

Your eye actually works the same way. The light gets flipped going through your eyes, since they’re small holes, too, and when it hits the back of your eye and starts to travel to your brain the whole world is upside-down! Luckily, your brain knows better and flips it back right-side up for you.

Experiment with the size of the pinhole. You can wiggle the toothpick around in the hole to make it bigger or use something else to make the hole bigger. Bigger holes will let more light through so you can see dimmer objects, but they will make it harder to focus and get a good view of what you’re looking at.  If you decide your hole is too big, you can always cover it with a small piece of electrical tape and make a new hole.

We got this activity from The Children’s Museum of Indianapolis.  If you liked it, check out their other activities!

Scientists work all over the world, in labs and offices, in jungles and desserts, even in the oceans and at the South Pole.  One of the many things they do is try to find animals and plants that no one has ever found before.  Right now, we know of about 1,600,000 species on our planet – and that’s a LOT of different plants, animals, and other living things – but scientists estimate there are around 8,700,000 species.  That means there are over 7 MILLION species still to be discovered on Earth!

For this activity, you get to create your very own, unique species.  How?  By making a rock creature!

You’ll need:
Googly eyes
Pipe cleaners and other things to decorate with
Some crayons
A rock
Glue
A piece of parchment paper

1. Preheat the oven to 350 degrees
2. Place the parchment paper on an oven proof baking sheet.
3. Figure out which side of your rock you want to be the top of your new creature. Place your rock, that side up, on the parchment paper.
4. Once the oven is preheated, heat the rock in the oven for about ten minutes. (Use parental help if needed.)
5. Get your crayons ready while you are waiting.
6. Carefully take the tray out of the oven and place it on a heat-safe surface.
7. Without touching the hot rock with your fingers, draw on it with your crayons. As you color, the wax of the crayons will melt, giving your rock a colorful shell.
8. Once your rock is cool, glue on the eyes and use other items to decorate your creature.  She’s your creature!  Will she be a bug?  A bird?  A mammal?  Something else?  Make her as wonderful and unique as you!

Check out this adorable creature from a fellow camper!

Whether you are camping in the jungle while on a research expedition, trying to secure parts for an experiment in a lab, or any of thousands of other possibilities – knots are VERY useful to know.

For this activity, you will need:
6 pieces of thin rope, about 18″ long each (about 9 feet total)
2 different colored tapes
1 piece of dowel
1 piece of cardboard

The first step is to assemble your practice board.
To do so:
Cut your cardboard to be about 3 inches wide and 8 inches long.
Punch pairs of holes along the length of the cardboard as in the image below.

Next, you need to prepare your rope.
To do so:
Cut the rope into 18″ long pieces.
For each piece wrap each end in a different color tape.  You can see the white and black ends of our ropes in the image below.  Many “How to tie knots” books and websites will use different colored ends to help you tell which side of the rope to use when tying the knot.

Now thread each rope piece through a pair of the holes in your knot board.  We suggest you put the same colored ends all on the same side of the board.

Next, you need to learn a little vocabulary.

• Bend – When you join two ropes together.
• Bight – a “U” shape in your rope
• Hitch – When you attach a rope to something else.
• Loop –
• Standing End – The end of the rope you are not actively using.
• Standing Part – The length of rope between the Standing End and where you are working to make a knot.
• Tail or Working End – The end of the rope you are working with to make a knot.

Now you are ready to start!  We suggest starting with the overhand knot and the half hitch. These two knots are used in many other knots and they are useful on their own!  Both are on the top row of our sample board, using the dark blue rope.

For our sample board, we also used the overhand knot to secure the right hand side of our yellow, purple, and red ropes so they wouldn’t pull back out of the board.

You’ll find links below to websites that specialize in teaching how to tie knots.  For each knot, we have two links.  Pick the one that works best for you. They both have lots of good information about when to use the different knots.

Overhand Knot (right side of our dark blue rope)
101 Knots or Animated Knots

Half Hitch (left side of our dark blue rope)
101 Knots or Animated Knots

Two Half Hitches (yellow rope)
101 Knots or Animated Knots

Clove Hitch (purple rope)
101 Knots or Animated Knots

Square Knot (pink rope)
101 Knots or Animated Knots

Sheet Bend (light blue rope)
101 Knots or Animated Knots

Bowline (red rope)
101 Knots or Animated Knots

Have you ever watched an action movie or a cartoon where the heroes have to crawl through a room filled with lasers?

Want to try it yourself?  Here’s how!

You’ll need:

• Blue painter’s tape
• Roll of crepe paper

String the crepe paper across a hallway or doorway, using the painter’s tape to attach the ends to the walls.

Try to move through your maze without breaking any of the strands.
Did you manage to do it?
Move the strands around and try again!

We found this fun idea here.  Check out their other ideas, great for days when you can’t get outside.

Tops are fun and easy to make! You’ll need:

• Two sheets of Origami paper
• A toothpick
• A pin
• Glue

Since Origami instructions can be tricky to write and hard to follow when the instructions aren’t well done, here’s a video that shows you exactly what to do, step by step…

How to Make an Origami Top

As she mentions in the video, if the hole for the toothpick gets too big, the top won’t work well.  If you find your top isn’t spinning well anymore, try adding a small drop of glue where the toothpick goes into and out of the paper.  Let it dry completely before playing with it again.

Here’s a puzzling question for you…
In the picture above where the top is actually spinning, why is one of the orange sides so much larger than the other orange side?

Tie-dying isn’t hard to do, especially when you use a Sharpie!

You’ll need:
A t-shirt to dye
At least one Sharpie marker
Rubber Bands
A pipette
8 to 16 oz of rubbing alcohol (also called isopropyl alcohol – this can be purchased in the first-aid section of any drug store)

We suggest watching this video to understand the process before you proceed:
Tie-dying with a Sharpie

(1) Wash and dry your t-shirt.  Don’t use fabric softener or dryer sheets.

(2) Pick your pattern. You’ll find instructions for how to fold your fabric to make many of the traditional designs here.
Please note, the folding instructions say your shirt should be wet. Since we are using Sharpies, not liquid dye, your shirt actually needs to be DRY.

(3) Following the method you picked, fold your DRY shirt and secure it with the rubber bands, as needed.

(4) Before moving on to the next step, take a moment and protect your work surface. You don’t want the Sharpie to stain the furniture, floor, or other surfaces.  You can work outside in the grass or use a trash bag or other piece of plastic to protect the surface.

(5) Color the sections of your folded shirt with your Sharpie. Don’t forget to flip it over and color the back side too!  We recommend MORE color (less white areas) than in the image below.

(6) Let your colored t-shirt sit for at least 24 hours. The longer it sits (even a few days!), the better the sharpie stains the fabric.

(7) For this next step, you need to protect the surface under your shirt or work outside in the grass.  Anything under your shirt may be stained by the marker!
Using the pipette, add rubbing alcohol on the different sections of your tied-up shirt to make the marker color bleed.  Don’t forget to flip it over to do the back.

(8) Let your shirt dry completely.  This may take until tomorrow! Don’t forget, while your shirt is still wet, anything underneath will be stained by the marker.

(9) Once it is dry, take off the rubber bands and open up your shirt.

(10) Once you are certain your shirt is completely dry, you need to decide what to do next.  We experimented with several methods to “set” the ink, so it doesn’t wash out in the laundry, but we didn’t find one that worked well. Here’s what we tried:

We didn’t do anything to Sample #1.  It is our experimental control.
Sample # 2 was ironed with a hot iron for 5 minutes.
Sample #3 was put in a hot dryer for 15 minutes.
Sample #4 was soaked in white vinegar for 30 minutes. It was allowed to dry and then was ironed.
Sample #5 was soaked in white vinegar for 30 minutes. It was allowed to dry and then was put in a hot dryer.
Sample #6 was soaked in salt water for 30 minutes. It was allowed to dry and then was ironed.
Sample #7 was soaked in salt water for 30 minutes. It was allowed to dry and then was put in a hot dryer.
Afterwards, all seven samples were hand washed in the sink and hung up to dry.

As a last step, we washed all seven samples in the washing machine.  As you can see, all of the samples look a lot like Sample #1.  We have to conclude that these “setting the ink” methods don’t seem to work.