S03E33: Biosquare
As a science assignment, Arnold and Helga have to work together, and get along with each other, for 24 hours in the Sunset Arms greenhouse.
Previous Episode 
Season 1
Downtown as Fruits
S1E1 / 07 Oct 1996
Eugene's Bike
S1E2 / 07 Oct 1996
The Little Pink Book
S1E3 / 09 Oct 1996
Field Trip
S1E4 / 09 Oct 1996
Arnold's Hat
S1E5 / 14 Oct 1996
Stoop Kid
S1E6 / 14 Oct 1996
Helga's Makeover
S1E7 / 16 Oct 1996
The Old Building
S1E8 / 16 Oct 1996
6th Grade Girls
S1E9 / 04 Nov 1996
The Baseball
S1E10 / 04 Nov 1996
Heat
S1E11 / 11 Nov 1996
Snow
S1E12 / 11 Nov 1996
Operation Ruthless
S1E13 / 18 Nov 1996
The Vacant Lot
S1E14 / 18 Nov 1996
The List
S1E15 / 25 Nov 1996
Haunted Train
S1E16 / 25 Nov 1996
Mugged
S1E17 / 02 Dec 1996
Roughin' It
S1E18 / 02 Dec 1996
Door #16
S1E19 / 09 Dec 1996
Arnold as Cupid
S1E20 / 09 Dec 1996
Arnold's Christmas
S1E21 / 14 Dec 1996
Benchwarmer
S1E22 / 16 Dec 1996
Cool Jerk
S1E23 / 16 Dec 1996
Das Subway
S1E24 / 23 Dec 1996
Wheezin' Ed
S1E25 / 23 Dec 1996
Arnold the Tutor
S1E26 / 30 Dec 1996
Gerald Comes Over
S1E27 / 30 Dec 1996
Spelling Bee
S1E28 / 06 Jan 1997
Pigeon Man
S1E29 / 06 Jan 1997
Olga Comes Home
S1E30 / 13 Jan 1997
Sally's Comet
S1E31 / 13 Jan 1997
Abner Come Home
S1E32 / 20 Jan 1997
The Sewer King
S1E33 / 20 Jan 1997
False Alarm
S1E34 / 27 Jan 1997
World Records
S1E35 / 27 Jan 1997
Magic Show
S1E36 / 03 Feb 1997
24 Hours to Live
S1E37 / 03 Feb 1997
Arnold's Valentine
S1E38 / 14 Feb 1997
Season 2
Save the Tree
S2E1 / 22 Sep 1997
New Teacher
S2E2 / 22 Sep 1997
Helga's Love Potion
S2E3 / 24 Sep 1997
Gerald's Secret
S2E4 / 24 Sep 1997
The Big Scoop
S2E5 / 29 Sep 1997
Harold's Kitty
S2E6 / 29 Sep 1997
Longest Monday
S2E7 / 01 Oct 1997
Eugene's Pet
S2E8 / 01 Oct 1997
Monkey Business
S2E9 / 06 Oct 1997
Big Caesar
S2E10 / 06 Oct 1997
Ransom
S2E11 / 08 Oct 1997
Ms. Perfect
S2E12 / 08 Oct 1997
Arnold's Halloween
S2E13 / 27 Oct 1997
Arnold Saves Sid
S2E14 / 13 Oct 1997
Hookey
S2E15 / 13 Oct 1997
Freeze Frame
S2E16 / 15 Oct 1997
Phoebe Cheats
S2E17 / 15 Oct 1997
Mud Bowl
S2E18 / 20 Oct 1997
Gerald Moves Out
S2E19 / 20 Oct 1997
The High Life
S2E20 / 22 Oct 1997
Best Friends
S2E21 / 22 Oct 1997
Steely Phil
S2E22 / 29 Oct 1997
Quantity Time
S2E23 / 29 Oct 1997
Eating Contest
S2E24 / 03 Nov 1997
Rhonda's Glasses
S2E25 / 03 Nov 1997
Helga's Boyfriend
S2E26 / 05 Nov 1997
Crush on Teacher
S2E27 / 05 Nov 1997
Hall Monitor
S2E28 / 10 Nov 1997
Harold's Bar Mitzvah
S2E29 / 10 Nov 1997
Coach Wittenberg
S2E30 / 12 Nov 1997
Four-Eyed Jack
S2E31 / 12 Nov 1997
Eugene Goes Bad
S2E32 / 17 Nov 1997
What's Opera, Arnold?
S2E33 / 17 Nov 1997
Tour de Pond
S2E34 / 24 Nov 1997
Teachers' Strike
S2E35 / 24 Nov 1997
Runaway Float
S2E36 / 01 Dec 1997
Partners
S2E37 / 01 Dec 1997
Season 3
Helga Blabs It All
S3E1 / 31 Aug 1998
Harold the Butcher
S3E2 / 31 Aug 1998
Dangerous Lumber
S3E3 / 02 Sep 1998
Mr. Hyunh Goes Country
S3E4 / 02 Sep 1998
Casa Paradiso
S3E5 / 07 Sep 1998
Gerald's Tonsils
S3E6 / 07 Sep 1998
Arnold's Room
S3E7 / 09 Sep 1998
Helga vs. Big Patty
S3E8 / 09 Sep 1998
Stinky Goes Hollywood
S3E9 / 16 Sep 1998
Olga Gets Engaged
S3E10 / 16 Sep 1998
Curly Snaps
S3E11 / 23 Sep 1998
Preteen Scream
S3E12 / 23 Sep 1998
Grandpa's Birthday
S3E13 / 30 Sep 1998
Road Trip
S3E14 / 30 Sep 1998
Sid's Revenge
S3E15 / 07 Oct 1998
Roller Coaster
S3E16 / 07 Oct 1998
The Aptitude Test
S3E17 / 14 Oct 1998
Oskar Gets a Job
S3E18 / 14 Oct 1998
Arnold Betrays Iggy
S3E19 / 19 Oct 1998
Helga and the Nanny
S3E20 / 19 Oct 1998
Career Day
S3E21 / 21 Oct 1998
Hey Harold!
S3E22 / 21 Oct 1998
Best Man
S3E23 / 02 Nov 1998
Cool Party
S3E24 / 02 Nov 1998
Arnold & Lila
S3E25 / 04 Nov 1998
Grand Prix
S3E26 / 04 Nov 1998
Arnold's Thanksgiving
S3E27 / 18 Nov 1998
Helga's Show
S3E28 / 25 Nov 1998
The Flood
S3E29 / 25 Nov 1998
Phoebe Takes the Fall
S3E30 / 07 Dec 1998
The Pig War
S3E31 / 07 Dec 1998
Part Time Friends
S3E32 / 07 Dec 1998
Biosquare
S3E33 / 07 Dec 1998
Crabby Author
S3E34 / 28 Dec 1998
Rich Kid
S3E35 / 04 Jan 1999
Girl Trouble
S3E36 / 04 Jan 1999
School Dance
S3E37 / 04 Jan 1999
School Play
S3E38 / 08 Mar 1999
Season 4
Full Moon
S4E1 / 10 Mar 1999
Student Teacher
S4E2 / 10 Mar 1999
Big Gino
S4E3 / 15 Mar 1999
Jamie O in Love
S4E4 / 15 Mar 1999
Eugene's Birthday
S4E5 / 17 Mar 1999
Stinky's Pumpkin
S4E6 / 17 Mar 1999
The Beeper Queen
S4E7 / 29 Mar 1999
Oskar Can't Read?
S4E8 / 29 Mar 1999
Dinner for Four
S4E9 / 31 Mar 1999
Phoebe Skips
S4E10 / 31 Mar 1999
Helga's Parrot
S4E11 / 05 Apr 1999
Chocolate Turtles
S4E12 / 05 Apr 1999
Love and Cheese
S4E13 / 07 Apr 1999
Weighing Harold
S4E14 / 07 Apr 1999
Back to School
S4E15 / 11 Sep 1999
Egg Story
S4E16 / 11 Sep 1999
It Girl
S4E17 / 18 Sep 1999
Deconstructing Arnold
S4E18 / 18 Sep 1999
Grudge Match
S4E19 / 25 Sep 1999
Polishing Rhonda
S4E20 / 25 Sep 1999
Weird Cousin
S4E21 / 09 Oct 1999
Baby Oskar
S4E22 / 09 Oct 1999
Grandpa's Sister
S4E23 / 16 Oct 1999
Synchronized Swimming
S4E24 / 16 Oct 1999
Helga Sleepwalks
S4E25 / 23 Oct 1999
Fighting Families
S4E26 / 23 Oct 1999
Headless Cabbie
S4E27 / 30 Oct 1999
Friday the 13th
S4E28 / 30 Oct 1999
Veterans Day
S4E29 / 06 Nov 1999
Helga on the Couch
S4E30 / 04 Dec 1999
Dino Checks Out
S4E31 / 11 Dec 1999
Season 5
Monkeyman!
S5E1 / 04 Mar 2001
Buses, Bikes, and Subways
S5E2 / 04 Mar 2001
Helga's Masquerade
S5E3 / 11 Mar 2001
Mr. Green Runs
S5E4 / 11 Mar 2001
Sid the Vampire Slayer
S5E5 / 18 Mar 2001
Big Sis
S5E6 / 18 Mar 2001
Bag of Money
S5E7 / 05 Apr 2001
Principal Simmons
S5E8 / 05 Apr 2001
New Bully on the Block
S5E9 / 12 Apr 2001
Phoebe Breaks a Leg
S5E10 / 12 Apr 2001
Helga's Locket
S5E11 / 19 Apr 2000
Sid and Germs
S5E12 / 19 Apr 2001
Suspended
S5E13 / 26 Apr 2000
Ernie in Love
S5E14 / 26 Apr 2001
Parents Day
S5E15 / 10 May 2001
Summer Love
S5E16 / 21 Jun 2001
Stuck in a Tree
S5E17 / 05 Jan 2002
Rhonda Goes Broke
S5E18 / 05 Jan 2002
Beaned
S5E19 / 12 Jan 2002
Old Iron Man
S5E20 / 12 Jan 2002
Arnold Visits Arnie
S5E21 / 26 Jan 2002
Chocolate Boy
S5E22 / 26 Jan 2002
Harold vs. Patty
S5E23 / 03 Feb 2002
Rich Guy
S5E24 / 03 Feb 2002
April Fool's Day
S5E25 / 01 Apr 2002
Gerald's Game
S5E26 / 27 Apr 2002
Fishing Trip
S5E27 / 27 Apr 2002
Married
S5E28 / 11 May 2002
On the Lam
S5E29 / 01 Jun 2002
Family Man
S5E30 / 01 Jun 2002
The Racing Mule
S5E31 / 14 Oct 2002
Curly's Girl
S5E32 / 14 Oct 2002
The Journal (1)
S5E33 / 11 Nov 2002
The Journal (2)
S5E34 / 11 Nov 2002
Timberly Loves Arnold
S5E35 / 28 Jan 2003
Eugene, Eugene!
S5E36 / 28 Jan 2003
Ghost Bride
S5E37 / 11 Nov 2003
Gerald vs. Jamie O
S5E38 / 11 Nov 2003
A Day in the Life of a Classroom
S5E39 / 15 Nov 2003
Big Bob's Crisis
S5E40 / 15 Nov 2003
Phoebe's Little Problem
S5E41 / 08 Jun 2004
Grandpa's Packard
S5E42 / 08 Jun 2004
Spencer Klein
Arnold (voice)
Francesca Marie Smith
Helga Pataki (voice)
Jamil Walker Smith
Gerald Johanssen (voice)
Olivia Hack
Rhonda Wellington Lloyd (voice)
Anndi McAfee
Phoebe Heyerdahl (voice)
Justin Shenkarow
Harold Berman (voice)
Blake McIver Ewing
Eugene Horowitz (voice)
