L4 · Comparing with a third object when things cannot move

Learning goal

“I can use a third thing to compare two things that cannot move.”

Third object — a thing we carry from one thing to the other to compare them.

Cannot move — stays in one place, like a tree or a door.

In between — in the middle of two things.

Just reaches — ends right at the top or the edge, not past it.

Worked example

Two trees grow in the yard. Trees cannot move, so we cannot stand them side by side. We use a long rope as our third object. Step 1: Hold the rope beside Tree 1. The rope's top is below Tree 1's top. Tree 1 is taller than the rope. Step 2: Carry the SAME rope to Tree 2. The rope's top is above Tree 2's top. The rope is taller than Tree 2. Step 3: Put it together: Tree 1 is taller than the rope, and the rope is taller than Tree 2. So Tree 1 is taller than Tree 2. Say it plainly: the third object goes in the middle. It must be the SAME object both times.

Check yourself — explain it

Why do we carry the rope to the trees?

Paired problem — example still visible

A ribbon just reaches the top of the bookshelf. The same ribbon does not reach the top of the cabinet. Which is taller, the bookshelf or the cabinet? -> The cabinet (the ribbon matches the bookshelf but falls short of the cabinet)

Faded completion — last step is yours

"A stick is longer than the plant. The same stick is shorter than the shelf. The shelf is ___ than the plant." -> taller

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8 scored questions with a 3-rung hint ladder. Mastery needs 7/8 plus both gate questions.

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