Montessori Math Lesson Equivalence & Crisis of Nine Tray

Equivalence Crisis Tray – Montessori Math Lesson

Equivalence Tray – Presentation I

Invite the child to see some new work with the golden beads. Spread a mat: “This is the equivalence tray. Some people call it the Crisis of Nine tray. Let’sd look at these beads and count them. We’ll start with the units.”

Count the units from their tray into the mat below in a vertical line, touching each other.
“Ten units is the same as a ten bar. When we have a ten bar we have to move to a new place. We can’t stay in the unit’s place anymore.”
Use the same approach and language with tens/hundreds and hundreds/thousand: “Ten bars is the same as a hundred square. When we have a hundred square we have to move to a new place…”

Presentation II – Exchanging

Return to the row of units: “Now, let’s count these again.” Make a big deal of moving to the ten’s place and picking up a ten bar “because ten units are the same as one ten.” Continue on to the thousand cube by counting the hundred squares.
Summarize and quiz the child: “ten units make what? Ten bars make what?” etc.

Variations

Use separate mats for each quantity so the child must move his body considerably to count the beads
Ask the child to give you or to bring to you various quantities. Occasionally ask for ten of something to check if the child understands the exchange.