Big Friends Bridge — Lesson 44: Big friends: plus 5
Big friends: plus 4 and plus 3 →Lesson 44: Big friends plus 5 on an abacus
Level 4, Big Friends Bridge. When the top bead is already down, the big friend helps.
What your child does, card by card
Big friends: plus 5. 5 and 5 make 10. PlayBuddy opens the lesson: “The big friend of five is five. They are twins.”
3 + 5 = 8: the top bead is free. Bring it down. The abacus makes 3, then clears. Here the hands lead: they show 3 and 8, and a moment later the beads copy each one. Each label lights in turn: “Start at 3” and “+5: the top bead = 8”. After the show, the child can touch: “Lesson 14: plus 5 is the top bead.”
6 + 5: the top bead is down already. The top beads are outlined in yellow while the kids explain. The beads show 6 and go back to zero. “Start at 6” and “+ 5? Top bead is down” glow on the card in step with the beads. The card ends on a touch: “It cannot come down again. So add a ten!”
Plus 5: top bead up, one ten on: 10 is 5 and 5. So a ten is 5 too many. First the abacus shows the rule bead by bead (“−5: the top bead goes up”, “+10: one ten” and “+5 = −5 +10”). Next it is your child's turn: work out 6 + 5 and 9 + 5, the ring marking the top bead before the friend.
First a reminder (“2 + 5, then 5 more”): the beads build 2, 7, 2 and 12, ring by ring, while your child watches. First the top bead is free: bring it down. Then it is down: send it up, add a ten.
Try it: your child works out 5 + 5, 7 + 5 and 8 + 5, with a green ring on the next bead to move.
Then a short practice without rings: work out 6 + 5, 3 + 5, 9 + 5, 5 + 5 and 7 + 5, each round starting from its own number.
In Copy me the drawn hand holds up 11, 14 and 10 in turn, and your child copies each one in beads.
In your head: the abacus is covered and your child works out 5 + 5, 7 + 5 and 9 + 5, showing each answer on the drawn fingers.
You're ready! Top bead already down? Send it up and add a ten.
What this lesson trains
About five minutes and 16 answers. Altogether the child makes 24 bead moves (10 with the top bead, 14 with bottom beads). Up to 14, read and set from the left. Then 3 quick looks in your head. 9 of the 10 sums need a big friend (“+5 = −5 +10”); the others use free beads.
Your child’s first moves: work out 5 + 5, 7 + 5 and 8 + 5.
Fingers and hands
Below the abacus the drawn hands show zero and 3, 5, 6, 7, 8, 9, 10, 11, 12, 13 and 14 here, finger for bead: the left hand counts the tens, the right hand the ones.
+5 on the fingers: the right hand lets 5 go and the left hand opens one more finger for the ten (−5 +10).
On “3 + 5 = 8” 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.
Copy me turns it round: 11, 14 and 10 appear on the hand first.
What PlayBuddy and PlayType say
PlayBuddy: “The big friend of five is five. They are twins.”
PlayBuddy: “Adding five is the top bead's job.”
PlayBuddy: “No room on this rod. Ask the big friend.”
PlayBuddy: “Don't clear. The beads keep the answer.”
Stars
Three stars for up to 1 slip in 16 answers, two stars for up to 4.