STEM field: Electrical Engineering

Materials that allow an electric current to move easily through them are called conductors. Some materials use electrolytes, or salts, to move this electric charge. Since playdough has salt in it anyways, it’s always known to be weakly conducting. Two new recipes were developed - 1) to make the play dough very conductive by adding extra salts, and 2) an extra insulating (meaning, not conducting) recipe so that you can build more complicated circuits without shorting them.

What you’ll need: Water, flour, salt, cream of tartar, vegetable oil, food coloring
Recipe:
1 cup water
1.5 cups flour
¼ cup salt
3 T cream of tartar
1 T vegetable oil
food coloring

Dr. Mom’s tips:
Try testing your circuit out first with a small piece of playdough. The longer your circuit is, the more resistance you’ll get (and the less current that’s going to make it to your light bulb). You can use a multimeter to check your current output!

STEM field: Physics/Optics 

Hologram projectors use a theatre trick discovered in the 1500’s called “Pepper’s Ghost”. An image is reflected through a piece of glass (or plastic) which has been placed at a 45 degree angle to the viewing frame. When the background is dark, the holographic image is easier to see. How do you think the angle of contact will change the placement of the hologram image? Print out the image on the left.

What you’ll need:
1 smart mobile phone, scissors, 1-2 transparency film, clear tape

Dr. Mom’s tips:
It’s ok if your projector is a bit wobbly. Try rotating it on your phone and looking from different angles till you see the cool effect. Check out our youtube hologram video or try making your own!

STEM Field: Physics

Ever wondered why spinning soccer or baseballs seem to curve, drop, or fly without regard to gravity? It’s the same reason this Magnus effect glider stays in the air! The glider’s spinning direction pushes the air and causes a pressure difference. The glider is then pushed towards the faster moving area (lower air pressure). Try rolling the rubber bands in opposite directions- how does it change the flight path of the glider?

What you’ll need: Two plastic cups, tape, and several rubber bands

Dr. Mom’s tips:
Only hold the glider on to the loose end of the rubber bands. When you release the cup, you want it to be free to fly!

STEM field: Physics/Optics

The camera obscura is the simplest kind of camera you can imagine, because it uses a tiny hole to focus light instead of a lens. A small hole will give a focused image; the tradeoff is that the image will be relatively dark since not a lot of light can pass through that small hole. The image you’ll see will be upside down and backwards- why do you think that is?

What you’ll need: Cardboard tube, foil, tracing/wax paper, tape, scissors, toothpick

Dr. Mom’s tips: Make sure there isn’t any light leaking in to your camera by taping the tube parts very well! (remember the image isn’t very bright).

STEM field: Mathematics

A mobius strip is a surface that doesn’t end, and it’s made by joining the ends of a rectangular strip after twisting one end through 180 degrees. The hexaflexagon is just a mobius strip with some extra twists. That’s why it keeps turning inside out and never ends!

What you’ll need: a printer, scissors and tape

Print out the image to the left, and follow the folding instructions or watch the how-to video

Dr. Mom’s tips:
Make sure your triangles are folded exactly on the lines - this will make it turn a lot more easily.

STEM field: Electrochemistry

Any fruit/vegetable battery is an electrochemical battery, which uses a chemical reaction to move electrons. Moving electrons are the same thing as an electric current. In our battery, the zinc in the nail reacts with the copper wire in a kind of reaction where electrons are transferred. The electrons flow through the wires to complete the chemical reaction, and we can use that electricity to light up LEDs or power tiny machines. What other fruits or vegetables can you use? Give it a try!

What you’ll need:
3 baby pumpkins, 1 LED bulb, 3 pieces of copper wire, 3 zinc nails, 3 electrical wires with mini clamps

Dr. Mom’s tips:
One tiny pumpkin won’t be enough to power a LED, which is why we use three in a series. Make sure you’ve connected them as is shown in the picture.
 

STEM field: Optics

Light is basically radiations in wavelengths that are visible to our eyes. These wavelengths can be separated, which allows us to see different colors. One way to separate colors is using filters (yes, just like those on Instagram!). Filters keep certain wavelengths out and allow other wavelengths to pass through. We see the colors that pass through. Red filters make blue, purple, green, and brown appear black; & red, yellow, orange, and pink to disappear.

What you’ll need: Cardstock, red acetate, scissors, tape, red and blue crayons.

Dr. Mom’s tips:
Make sure the red acetate is clear - you can use several layers if it’s too thin.
 

Pesach (Passover) is all about asking questions, and we have some good ones for you!

Find out why the Pesach foods smell like they do, and learn about the chemistry behind Passover.

Enjoy this FREE Science-Seder-Plate made by Dr. Mom, and make your own personalized Seder plate.

STEM field: Physics

Catapults of all kinds use simple machines- levers- combined with a form of stored energy. When we release the popsicle stick we release this energy and let the projectile fly! Try putting the bottle cap closer to the stack of rubber bands - does it change how far the projectile goes? What do you know about levers that can explain this?

What you’ll need: 10 popsicle sticks, 4-6 rubber bands, glue, a bottle cap,

Dr. Mom’s tips:
Leave yourself enough room above the bottle cap for your finger to push down the popsicle stick!