X-Men 101: #56 - X-BABIES

For a short time, Mojo turned the X-Men into children. To return them to normal, the New Mutants were forced to "graduate," becoming the X-Men in order to beat Mojo.
(Uncanny X-Men Annual #10)

X-Men 101: #55 - TAKE ONE

The teens of Generation X weren't the White Queen's first students. The Hellions were the White Queen's evil version of the New Mutants. Most of them were killed by Trever Fitzroy and his Sentinels.
(New Mutants #16, Uncanny X-Men #281)

X-Men 101: #54 - BLOWN AWAY

The X-Mansion has often been breached by evil mutants many times which has caused it's destruction over and over again. It was demolished in a battle with the Sidri in Uncanny X-Men #154 and atomized by Mister Sinister in Uncanny X-Men #243. However, certain portions of the mansion, such as sub-basements, survived both attacks. When Onslaught revealed himself and fought the X-Men (X-Men #54) the mansion took heavy damage, though was quickly repaired in-between issues after the "Onslaught" storyline. In Operation: Zero Tolerance, Bastion forced Jubilee to reveal the mansion's defenses. He then stripped down the mansion, having nearly everything inside the mansion removed. After defeating Bastion, the X-Men moved back into the mansion and restocked it, as detailed in X-Men #70. Most recently, the X-Mansion survived an assault by the Shi'ar Imperial Guard in New X-Men #122-126 as well as a riot by students led by Quentin Quire in New X-Men #134-138. In the Planet X storyline of New X-Men #146-150, however, the X-Mansion was destroyed; the rebuilding process could be seen in New X-Men #155-156. In the wake of M-Day the mansion was infiltrated by followers of the Reverend William Stryker in an attempt to wipe out the students, resulting in some structural damage and several casualties. Then the mansion was destroyed when the Danger Room became sentient and summoned local machinery to attack the structure. The mansion was also damaged when Mr Sinister's new team of Marauders attacked the mansion. More recently, a fight between the Hulk and several mutants damages the mansion. In the Messiah Complex storyline, the Mansion is completely destroyed by attacking Sentinels. Where do they get the money to rebuild.

X-Men 101: #53 - MENTAL NOTE

As a young girl, Jean Grey felt the emotions of a dying friend via telepathy, which left her withdrawn. Her parents sought out Charles Xavier's help and he placed mental barriers in her mind preventing her from using her telepathy until she was mature enough to handle it.
(Bizarre Adventures #27)

X-Men 101: #52 - OUCH!

Think Wolverine's healing factor is tough? He's survived being crucified, having the adamantium that laced his skeleton sucked from the pores of his skin and stopped a Brood egg from hatching inside of him.
(Uncanny X-Men #162, #251; X-Men #25)

X-Men 101: #51 - ANGEL CHEATS

While they were Xavier's students, Angel once paid Beast to write a term paper for him. Beast clued Xavier in on the scam and the Prof demanded that everyone mentally recite their papers. Angel was quickly busted.
(Uncanny X-Men #297)

X-Men 101: #50 - LONG LIVE THE KING

During his tenure as the X-Men's mentor, Magneto created an alliance with the Hellfire Club's Inner Circle by becoming its White King. All members of the Inner Circle were named after chess pieces.
(Uncanny X-Men #219)

X-Men 101: #49 - OLD FRIENDS

Not always enemies, Charles Xavier and Magneto were good friends when they were younger. Their friendship ceased when Magneto acted on his views of mutant world conquest.
(Uncanny X-Men #161, X-Men #-1)

X-Men 101: #48 - MIS-FIRE

Xavier's superpowered son Legion (David Haller) accidentally caused the "Age of Apocalypse" timeline. He'd traveled back in time to kill Magneto, but Xavier ended up being killed instead, creating a world where Xavier's X-Men never existed.
(X-Men #41)

X-Men 101: #47 - BAD KARMA

The New Mutant known as Karma was once possessed by the Shadow King and gained about 1000 lbs. He eventually left her body and she lost the weight while trapped in the Asgardian desert.
(New Mutants #30-#34)

X-Men 101: #46 - LOST LOVE

Before Cyclops and Jean Grey professed their love for each other, Angel also pined for Ms. Grey's affections. Wolverine has also professed a deep love for Jean, and though she has admitted an unexplainable attraction to Logan, she's never acted upon it.
(Classic X-Men #1)

X-Men 101: #45 - X-BABY

Professor X once "demoted" Kitty Pryde from the X-Men into the New Mutants. He was concerned that Kitty needed more training and education. But after she helped halt an attack by alien Sidrian Hunters on the X-Mansion, Xavier agreed to put her back on the X-Men.
(Uncanny X-Men #167-168)

X-Men 101: #44 - FEELING BLUE

Beast and Nightcrawler do not have blue skin, they have a fine coat of blue fur covering their bodies. Angel, on the other hand, really does have blue skin.
(Official Handbook of the Marvel Universe #2, #9)

X-Men 101: #43 - EX-MEN

Not all X-Men were just X-Men. Best has been a member of the Avengers and Defenders, while Angel and Iceman were both part of the Champions and the Defenders. Angel's wealth funded the Champions and, when he was a member, the Defenders.
(Avengers #137, Champions #1, Defenders #125)

X-Men 101: #42 - WHERE'S GILLIGAN?

Professor X recruited his new X-Team to rescue the original team, which was held captive by a living island called Krakoa. The mission was successful and the only original member to remain with the new team was Cyclops.
(Giant-Size X-Men #1)

X-Men 101: #41 - X-FILES

Before anti-mutant sentiments swept the nation, Xavier asked FBI agent Fred Duncan to help track down mutants in the U.s. so he could help train them in the use of their abilities. he FBI had been investigation mutants long before Xavier set up his school.
(Uncanny X-Men #2)

X-Men 101: #40 - UBER SENTINEL

Bastion, the leader of the mutant-hating Operation: Zero Tolerance, is actually an amalgamation of the Sentinels Nimrod and Master Mold. They merged right before being thrown into the transdimensional portal called the Siege Perilous.
(Uncanny X-Men #246-#247)

X-Men 101: #39 - NAZI HATER

When he was just a boy, Magneto was imprisoned in a Nazi concentration camp, along with his future wife, Magda.
(Classic X-Men #12)

X-Men 101: #38 - ADIOS, PROFESSOR

The New Mutants left Xavier's tutelage when they felt his dream of a peaceful coexistence with humans wasn't cutting the mustard. They joined up with Cable and called themselves X-Force.
(New Mutants #100, X-Force #1)

X-Men 101: #37 - X-REPLACEMENTS

Professor X created the New Mutants when he believed the X-Men were destroyed in space by the brood.
(Uncanny X-Men #165, Marvel Graphic Novel #4: The New Mutants)

X-Men 101: #36 - X-TRAITOR?

Gambit once worked for Mr. Sinister. His last two jobs for sinister were gathering the Mauraders and leading them into the Morlock tunnels, but Gambit was unaware of their plan to massacre the Morlocks.
(Uncanny X-Men #350)

X-Men 101: #35 - WINGING IT

When Angel's wings were amputated after they were damaged in battle, Angel fell into depression and tried to commit suicide. Apocalypse would take him in, giving him metal wings in return for his loyalty.
(X-Factor #15, #18)