Measured Response is Season 2 Episode 6.
In the gym, Six shows Five a trick his Buddy Blocks can do: turn into long rectangles, which he calls Buddy Sticks. They can also fly around while still in stick form and stack themselves on top of one another. Five is impressed, and then the alarm sounds, so they go to the control room as Three and Four inform them about the trouble.
Agent 72 reports that a girl is having trouble drawing: her felt pen keeps changing in length. Six decides to go out, and he lands on a wheelie bin.
Agent 44 reports additional problems: at a hotel, a man's trouser leg keeps shrinking and growing, as does another man's dinner knife somewhere else. Six and an agent notice in unison that the cleaner's broom is also growing and shrinking.
The Numberjacks and agents identify the pattern: things keep changing in length, and those things tend to come in pairs (for instance, the knife and fork). Five wonders who is causing the trouble and, as if on cue, the Shape Japer flies into view.
The Numberjacks know a solution: get everything back the right length. However, they don't know what the right length is, so Five asks the agents for advice. Agent 72 points out that the things came in pairs, so they just have to use the other thing (for instance, measure the correct length of the trouser leg using the other trouser leg).
They send brain gain to make the pairs match in length, but unfortunately the trouble isn't over. The man with the trousers now has his tie grow and shrink, and they can't use the same method with the tie since it doesn't have anything to match with. Then, the cleaner's mop starts to grow and shrink.
Five imagines a slide, tree, and street getting shorter and longer. The Shape Japer continues to change the length of ties and mops. Thankfully, Four finds a match— a man who is unaffected, and he's mopping whilst wearing a tie. Unfortunately, the man can’t help Six his tie and mop because he's concerned the Shape Japer will see, and change, them.
Luckily, Agent 72 has a plan: measure the tie and mop with the Buddy Sticks. As it turns out, the tie is two sticks long, while the mop is six. Thus, Three makes brain gain to make all the ties two sticks long and all the mops six sticks long.
Then, the Buddy Sticks "measure" the Shape Japer, making her stretch out and explode. Six comes back and they retell the mission.
In the gym, Five and Six watch the sticks dance, and Five asks the viewers if they have anything they could use as measuring sticks and, if so, use them.
Agents: 37, 44, 72
Numberjacks: Three, Four, Five, Six
Meanies: Shape Japer
Stays: Three, Four, Five