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Build Your Own Black Light Secret Message – Perfect for Trick or Treating!

We are always looking for new and fun science activities at the Steve Spangler Science Labs.This Halloween season we have really outdone ourselves with a new product line that includes Vampire Slime and Vampire Veins. We have also created this simple and easy craft that also teaches a lesson in the science of glow.

Some of the adults in the company may also sneak into Steve’s Playroom, turn off the lights and put together puppet shows with our black light projectors. I won’t tell if you won’t tell.

I’m also prepping to do this activity with 20 Brownie Girl Scouts this Tuesday. I can’t wait to see what they all come up with. I know it will be beyond anything that our Spangler lab rats have created the past few weeks.

This black light projector is perfect to take along Trick or Treating, not as a flash light, but as a fun way to say “Trick or Treat” or flash as you cross streets.

Let’s start with a lesson about Phosphorescence and Fluorescence.

Phosphorescence – Some materials glow after all the lights are turned off. This type of glow is called phosphorescence. “Glow in the dark” toys phosphoresce brightly in total darkness after being “charged” or excited by ordinary white or ultraviolet light. A phosphorescent material absorbs and slowly re-emits energy in the form of light. It will still glow after the lights are turned off. Remember those little stars you stuck to your roof as a kid? Those stars used a phosphorescent material to glow after you turned out the lights.

Fluorescence – Some glowing materials will only work in the presence of some form of radiation like ultraviolet light. These materials have a chemical property called fluorescence. Fluorescent materials absorb energy just like phosphorescent materials, but fluorescent materials re-emit their energy as light much quicker.  For example, fluorescent papers and poster boards glow in the daylight. They may seem to glow even brighter under black light (ultraviolet), but in either case, as soon as the light is removed, the glow stops. Fluorescent things do not glow in the dark all by themselves – they require some other form of energy such as ultraviolet light to “excite” them.


Glow Sticks
Glow sticks are yet another way that materials can glow in the dark. Glow sticks create their glow through a chemical reaction between different chemicals. The light that this chemical reaction produces is called chemiluminescence. Just like the other two types of materials, you can see chemiluminescent materials the best in the dark. It’s not a good idea to break open glow sticks to use the liquid inside. Most sticks contain a glass tube inside that shatters to mix the chemicals together. You don’t want to pour glass shards out for children to touch. The chemicals inside the glow stick aren’t incredibly toxic, but can cause eye and skin irritations and will stain.
Some highlighters use ink that contains dyes that are fluorescent. When you draw the designs with a highlighter, it probably looks like those designs will glow when you turn the lights off, but they don’t. The dyes in the highlighter ink require a black light to produce the special glow. Certain colors  and brands of highlighter do not fluoresce underneath the ultraviolet light. These highlighters do not contain fluorescent dyes.


  • Mini Black Light
  • Glue
  • Sharpie® highlighters (will fluoresce under a black light)
  • Scissors
  • Plastic cup
  • Pen
  • White paper


  1. Use a pen to trace the circumference of a plastic cup on a piece of white paper. Don’t use thick paper like card stock or construction paper. Just pull a piece of paper out of a printer… that’ll work perfectly!
  2. Use Sharpie highlighters to create brightly-colored designs within the circle you traced. Try using different colors when creating your design.
  3. Cut the traced circle out with a pair of scissors.
  4. Carefully poke a small hole in the bottom of the plastic cup using the scissors. Try to poke the hole as close to the center of the cup as possible.
  5. Apply a thin layer of glue around the edge of the circle. Make sure the glue is on the back side of the circle, away from your design, otherwise your design or message will be backwards. (Depending on what your design or message is, this could be a big deal!)
  6. Press the mouth of the cup onto the glue-covered edge of the paper circle. We recommend letting the glue dry before moving on to the next step, but hey… we aren’t here to slow you down. (Remember to clean up any glue that squeezed out and onto the table where you’re working. Happy parents make for happy scientists.)
  7. Now that your cup and design are attached, push the Mini Black Light’s bulb into the hole you poked in the bottom of the cup.
  8. Are you ready for this? Turn the lights off and turn on the Mini Black Light.
  9. Whoa! The ink from the highlighters glows in the ultraviolet light!

Fun Fall Activities & Events in Denver!

Looking for something fun to do in Denver now that fall is here?  Well, search no more!  Here is a great list of Free Days, Events, Festivals and Fun things to do right here in the Mile High area!  There is something for everyone on this list.  Be sure to check it out!


Botanic Gardens 720-864-3500
Friday, October 23

Botanic Gardens at Chatfield Park 303-973-3705
Friday, November 6
Friday, December 4

Denver Museum of Nature and Science 303-322-7009
Monday, November 2
Sunday, November 22

Denver Art Museum 720-865-5000
Free First Saturdays – the first Saturday of every month is free for Colorado residents; entry ticket is required for crowd control

Children’s Museum 303-433-7444
Free First Tuesdays – the first Tuesday of every month is free for Colorado residents from 4:00 – 8:00 pm

Denver Firefighter’s Museum 303-892-1436
Saturday, October 10
Saturday, October 31: Free admission for children in costume
Saturday, November 14: Colorado Residents Free Day

Denver Zoo 303-376-4800
Sunday, October 25
Sunday, November 8
Wednesday, November 11

Denver Museum of Miniatures, Dolls, and Toys
1880 Gaylord Street, Denver
First Sunday of every month, “pay what you can”


Dinosaur Discovery Days

First Saturday of the month, 10:00 am – 2:30 pm

Dinosaur Ridge – 16831 W Alameda Pkwy

The Hogback will be closed to vehicles while trained guides explain dinosaur evidence and answer questions; free activity booklet; fun activities for kids including the Stegosaurus Branding, the Edmontosaurus Bone Dig, the Grallator Track Lab ($1), the Future Illustrator Coloring Studio, the Cretaceous Crossroads Track Site, and Face Painting ($1)

Visitors can hike at their own pace or ride the Vanosaurus for $2 per person (children 4 and under ride free)

High Plein Air Arts Festival

November 14 through December 31, times and locations vary – check website

Golden Triangle Neighborhood – Lincoln between Speer and 13th Ave in Denver

Watch over 100 artists paint throughout the area; Paint Out locations include the Denver art Museum Plaza.

Third Thursday on 32nd

Third Thursday of the Month, May through November, 5:00-8:00 pm

Along 32nd Ave near Lowell

Free food, live music, store specials

First Fridays on Santa Fe

First Friday of the Month, May through December, 6:00-9:00 pm

Santa Fe Drive between 6th and 13th Avenues

Free food and drinks, live music, art, jewelry and other displays; history tours of the area offered at the same time

Golden Triangle First Fridays

First Friday of the Month, January through November, 5:00-9:00 pm

Golden Triangle Neighborhood – Lincoln between Speer and 13th Ave in Denver

Free shuttle bus to participating galleries; historic Byers-Evans House also open for these evenings

Golden First Fridays – 303-279-3113

First Friday of the Month, 5:00 – 8:00 pm

Downtown Golden

Cherry Creek North First Friday Gallery Walk –

First Friday of the Month, 5:00 – 8:00 pm

Cherry Creek North shopping district

Tours of the myriad art galleries in the district

Hay Bales and Tall Tales

First Saturday of the Month, 11:00 am – 12:00 pm

Four Mile House – 715 S Forest St in Glendale

A reading of a pioneer story followed by a wagon ride for the kids

Wild Rides – 303-289-0930

Year round starting at 9:00 am

Trolley tours of the wildlife on the former Rocky Mountain Arsenal

Free, but you must call for reservations

Heritage Square – 303-279-2789

Alpine slide, kiddie amusement rides, go karts, bumper and paddle boats, fishing, train, shopping, musical and children’s theater and much more in this replica of a Victorian main street

18301 W Colfax Ave in Golden

Celestial Seasonings Tea Factory –

On the hour, 10:00 am – 3:00 pm, Monday through Saturday; 11:00 am – 3:00 pm Sunday

4600 Sleepytime Drive in Boulder

45 minutes; no children under 5 in the factory; tea samples; gift shop

Denver Mint

On the hour, 8:00 am –3:00 pm, Monday through Friday, closed on federal holidays

Colfax and Cherokee in Denver

1 hour, reservations recommended; coin production in action; tight security so check website for restrictions; gift shop

Colorado State Capitol Building – 303-866-2604

9:15 am – 2:30 pm, Monday through Friday, closed on state and federal holidays

Colfax and Broadway in Denver

45 minutes; watch government at work and see an historic building

Coors Brewery – 303-277-2552

10:00 am –4:00 pm, Monday through Saturday

13th and Ford in Golden

45 minutes; beer samples (for 21+); gift shop

Anheuser Busch Brewery

10:00 am –4:00 pm, Thursday through Monday

2351 Busch Drive in Ft. Collins

1 hour; beer samples (for 21+); Clydesdales; gift shop


Looking for a listing of Fall Festivals, Corn Mazes, Pumpkin Patches, and Trick or Treat Options? Please click here for the list!

Do you know of something that isn’t on our list that should be included? Send an email to assistant editor, JoAnn at [email protected]

Fall Festivals & Halloween Events

Looking for some Fall Festivals to attend?  Need some Halloween Events for your Little Ghosts and Goblins?  Check out our list of fun things to do in the area!


For a complete listing of corn mazes and pumpkin patches throughout the state, check out this link.

Denver Botanic Gardens Corn Maze – 303-973-3705
Now through October 31:
Fridays 4:00 – 9:00 pm
Saturdays 10:00 am – 9:00 pm
Sundays 12:00-8:00 pm

Denver Botanic Gardens at Chatfield – 8500 Deer Creek Canyon Road Littleton, CO 80128

Admission – Members $8.00 Adults/$4.00 Kids; Non-members $10.00/$5.00; does not include admission to the Pumpkin Festival

Halloween Fun at Cottonwood Farms
Now through October 31:
Daily 10:00 am – 6:00 pm

Cottonwood Farms – SW corner of 75th and Arapahoe Streets in Boulder

Straw bale and corn mazes, working steam tractor and other farm equipment, animals, pumpkins and other fall items available for purchase

Fall Festival at Anderson Farms
Now through November 1:

Daily, 10:00 am to closing time varies by day, see website

Anderson Farms – 6728 WCR 3 ¾ Erie, CO 80516; off Hwy 52 between I-25 and Hwy 287

Corn maze, hay bale maze, wagon and barrel train rides, animals, pumpkin patch

Kid’s Alley – Weekends – $12.00 for unlimited carnival rides

Fall Fest Admission $10.00 Adults/$8.00 Kids (4-12) and seniors; discount coupons available on website

Pumpkin Festival – 303-973-3705
Saturday, October 10, and Sunday, October 11:
9:00 am – 5:00 pm

Denver Botanic Gardens at Chatfield – 8500 Deer Creek Canyon Road Littleton, CO 80128

Admission –$5.00 Adults/$3.00 Kids, children (3-15) in costumes are free; does not include admission to the Corn Maze

The Great Pumpkin Adventure– 303-659-5050
Saturday, October 10:
10:00 am

Berry Patch Farms – 13785 Potomac St., Brighton, 80601

Giant pumpkin contest; prizes awarded for largest, most unusual, and best dressed

Arvada Festival of Scarecrows – 303-420-6100
Saturday, October 10:
10:00 am – 3:00 pm

Olde Town Arvada – Grandview and Old Wadsworth

Scarecrow contest, hayride, pumpkin patch and parade of little goblins

Harvest Fest and Pumpkin Sale – 303-795-3950
Saturday, October 10:
10:00 am – 3:00 pm

Littleton Historical Museum – 6028 S. Gallup Street Littleton, CO 80120

Cider making, flour grinding, live music, wagon rides and food and beverages available on this 1860s farm

PumpkinFest – 303-739-7000
Saturday, October 10:
9:00 am – 4:00 pm

Delaney Farm – 170 S. Chambers Road Aurora; shuttles for parking

Pumpkin patch, hayrides, scarecrow making, ‘Jack-o-Launch’ contest, food

International Kite Festival
Saturday, October 11:
10:00 am – 4:00 pm

Stapleton Central Park (1/2 mile east of Quebec on Martin Luther King Blvd)

Children and Pet Parade, live music, giant kite battle, food and wine tent

2009 Refuge Roundup – Journey to the Old West
Saturday, October 17:
9 am – 3 pm

Rocky Mountain Arsenal National Wildlife Refuge, 56th and Havana

A FREE family celebration of the American West and National Wildlife Refuge Week featuring bison tours and hayrides*, dancing horses, a square dance exhibition team, Aztec dancers, sharp-shooting demonstrations, Buffalo Soldiers mounted cavalry drills and more!

*Reservations are required for bison tours and hayrides, call the U.S. Fish and Wildlife Service today at 303-289-0930.

Firehouse Ghosts – 303-892-1436
Saturday, October 24:
6:00 pm – 8:00 am (overnight)

Denver Firefighter’s Museum – 1326 Tremont Place, Denver

Old fashioned sleepover with spaghetti dinner, spooky movies, ghost stories and pumpkin carving


Victorian Halloween – 303-795-3950
Saturday, October 24:
6:00 – 8:00 pm

Littleton Historical Museum – 6028 S. Gallup Street Littleton, CO 80120

Apple bobbing, stories, fortune telling, refreshments, NO trick or treating


Trick or treatingBoo at the Zoo – 303-376-4800

Boo at the Zoo at Night:
Friday, October 30:
6:00 pm – 9:00 pm;
Advance registration required

Boo at the Zoo:
Saturday, October 31 and Sunday, November 1:
9:00 am – 5:00 pm

Denver Zoo – 2300 Steele St, north side of City Park

Family-friendly trick or treating and other Halloween activities

Regular admission price applies: $9.00 Adults/$5.00 Kids 3+, free for members

Children’s Museum: Trick or Treat Street – 303-433-7444

Thursday, October 29 and Friday, October 30:
9:00 am – 8:00 pm;

Saturday, October 31:
10:00 am – 8:00 pm

Children’s Museum of Denver – 2121 Children’s Museum Drive – I-25 and 23rd Ave

Family-friendly trick or treating and other kid-related Halloween events

Outside fun is free; Regular admission price apply inside: $7.50 ages 2+

The Wildlife Experience: Trick or Treat OFF the Street – 720-488-3325

Saturday, October 31:
9:00 am – 7:00 pm

The Wildlife Experience – 10035 S Peoria Parker – I-25 and Lincoln

Family-friendly trick or treating and other kid-related Halloween events

Admission $9.00 adults/$8.00 seniors/$6.00 kids 3-12, includes museum admission and treat bag

Garden of Goodies

Friday, October 30 and Saturday, October 31

Hudson Gardens – 6115 S. Santa Fe Drive in Littleton

Safe trick or treat street for little ghouls and goblins in the garden

Halloween Kids Fest

Friday, October 30 and Saturday, October 31, and Sunday, November 1:
10:00 am– 4:00 pm

Downtown Denver Aquarium

Lots of fall and Halloween-themed activities including a trick or treat reef

Aquarium admission fees apply

Forney Fall Fest

Saturday, October 31:
4:00-8:00 pm

Forney Transportation Museum – 4303 Brighton Blvd in Denver

Free refreshments, games, prizes, activities, and a piñata bash! All activities are indoors, where it’s heated, fun, and safe; community carnival rather than a haunted house; tons of trains, bicycles, motorcycles, carts, carriages, and cars to look at too.


Fall Leaves

To see our list of Fall Activities and Events in Denver, click here!

Do you know of something that isn’t on our list that should be included? Send an email to assistant editor, JoAnn at [email protected]