Small Friends Pond — Lesson 36: Small friends on the tens rod

What your child does, card by card

Small friends on the tens rod. The tens rod has a top bead too. PlayType opens the lesson: “Small friends live on the tens rod too.”

The tens rod counts like the ones rod: four beads of 10. A top bead of 50. Yellow marks the tens rod while the kids talk about it. The abacus makes 10, then clears. On the card, “10”, “20”, “30”, “40” and “50” light up one by one. Then the card invites a touch: “So 40 and 10 make 50, like 4 and 1 make 5.”

2 + 4, then 20 + 40: 4 tens: add 5 tens, take 1 ten back. The ones rod and the tens rod are outlined in yellow while the kids explain. The beads show 2 and 20 and go back to zero. Here the hands lead: they show 2, 7, 6, 20, 70 and 60, and a moment later the beads copy each one. Each label lights in turn: “2 + 4 = 6” and “20 + 40 = 60”. After the show, the child can touch: “The same two moves, on the tens rod.”

Watch me: 70, 20 and 30 appear on the beads one move at a time, each bead ringed in green before it goes. Like 7 − 4: top bead up, 1 bead back on. On the tens rod.

First a reminder (“34 + 43”): the beads build 34, 84, 74, 79 and 77, ring by ring, while your child watches. Tens first: add 4 tens. Then the ones: add 3.

Try it: your child works out 20 + 40, 70 - 40, 12 + 43 and 34 + 43, with a green ring on the next bead to move.

Then a short practice without rings: work out 30 + 40, 41 + 34, 70 - 40, 65 - 32 and 23 + 32, each round starting from its own number.

Copy me: the hand in the lower window shows 77, 60 and 55, one at a time, and your child makes the same number on the beads.

Then the beads hide and the sums 20 + 40, 70 - 40 and 34 + 43 are done in the head, the answer shown on the fingers.

You're ready! The tens rod has small friends too: the same trick, one rod to the left.

What this lesson trains

About five minutes and 15 answers. Altogether the child makes 36 bead moves (19 with the top bead, 17 with bottom beads). Up to 77, read and set from the left. Then 3 quick looks in your head. 9 of the 9 sums need a small friend (“+4 = +5 −1”, “−4 = −5 +1”, “+3 = +5 −2”, “−3 = −5 +2”, “−2 = −5 +3” and “+2 = +5 −3”); the others use free beads.

The first thing your child does: work out 20 + 40, 70 - 40, 12 + 43 and 34 + 43.

Fingers and hands

Below the abacus the drawn hands show zero and 2, 6, 7, 10, 12, 20, 23, 30, 33, 34, 41, 55, 60, 65, 70, 75 and 77 here, finger for bead: the left hand counts the tens, the right hand the ones.

+4 on the fingers: the thumb opens and one finger closes (+5 −1). −4 on the fingers: the thumb closes and one finger opens (−5 +1). +3 on the fingers: the thumb opens and 2 fingers close (+5 −2). −3 on the fingers: the thumb closes and 2 fingers open (−5 +2). −2 on the fingers: the thumb closes and 3 fingers open (−5 +3). +2 on the fingers: the thumb opens and 3 fingers close (+5 −3).

On “2 + 4, then 20 + 40” the hands move first and the beads follow, so your child sees that a finger and a bead move together: open a finger and a bead goes to the bar, close it and the bead goes back.

In Copy me the hand leads with 77, 60 and 55 and your child turns each into beads.

What PlayBuddy and PlayType say

PlayType: “Small friends live on the tens rod too.”

PlayType: “Ten, twenty, thirty, forty. And the top bead is fifty!”

PlayBuddy: “Five is one too many. So one bead goes back!”

PlayBuddy: “Top bead down, small friend off.”

PlayType: “Top bead up, small friend on.”

Stars

With 1 or fewer slips across the 15 answers your child earns three stars; 3 or fewer, two.