Big Friends Bridge — Lesson 42: Big friends: plus 7 and plus 6

What your child does, card by card

Big friends: plus 7 and plus 6. 7 and 3 make 10. 6 and 4 make 10. PlayType opens the lesson: “Same trick, new friend.”

8 + 9 = 17: a ten is 1 too many. Take 1 off first. 8 appears on the beads, then the rod clears again. Here the hands lead: they show 8, 7 and 17, and a moment later the beads copy each one. The labels “−1” and “+10 = 17” light up as each idea comes. “The trick of lesson 39.” Any bead or finger may be tapped afterwards.

4 + 7: only 5 more fit on this rod. Yellow marks the ones rod while the kids talk about it. The abacus makes 4, then clears. On the card, “Start at 4” and “+ 7? Only 5 fit” light up one by one. Then the card invites a touch: “7 will not fit. So add a ten!”

Plus 7: 3 off, one ten on: 10 is 7 and 3. So a ten is 3 too many. The beads act out the friend rule while “−3: the big friend”, “+10: one ten” and “+7 = −3 +10” light up; then your child must work out 4 + 7 and 8 + 7, a green ring on each bead in the friend's order.

Watch me: 4, 10, 9, 5 and 15 appear on the beads one move at a time, each bead ringed in green before it goes. 4 and 6 are big friends. All 4 beads go off. One ten goes on.

Try it puts a green ring on each next bead; your child works out 3 + 7, 9 + 6 and 4 + 6.

A tiny practice with no ring: work out 9 + 7, 4 + 6, 3 + 7, 2 + 7 and 9 + 6, each round starting from its own number.

Copy me: the hand in the lower window shows 11, 15 and 10, one at a time, and your child makes the same number on the beads.

Then the beads hide and the sums 4 + 7, 9 + 6 and 3 + 7 are done in the head, the answer shown on the fingers.

You're ready! Plus 7: take 3 off. Plus 6: take 4 off. Then add a ten.

What this lesson trains

16 answers in about five minutes. The tasks take 25 bead moves in all: 2 with a top bead and 23 with bottom beads. The largest is 16: tens and ones. Then 3 quick looks in your head. Friends do 9 of the 10 sums, by +7 = −3 +10 and +6 = −4 +10.

The first thing your child does: work out 3 + 7, 9 + 6 and 4 + 6.

Fingers and hands

Below the abacus the drawn hands show zero and 2, 3, 4, 7, 8, 9, 10, 11, 15, 16 and 17 here, finger for bead: the left hand counts the tens, the right hand the ones.

+7 on the fingers: the right hand lets 3 go and the left hand opens one more finger for the ten (−3 +10). +6 on the fingers: the right hand lets 4 go and the left hand opens one more finger for the ten (−4 +10).

On “8 + 9 = 17” 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 11, 15 and 10 and your child turns each into beads.

What PlayBuddy and PlayType say

PlayType: “Ten is one too many. So take one off first, then add the ten!”

PlayBuddy: “No room on this rod. Ask the big friend.”

Stars

With 1 or fewer slips across the 16 answers your child earns three stars; 4 or fewer, two.