Mix Mountain — Lesson 59: The mix: plus 6
The mix: plus 7, plus 8 and plus 9 →Lesson 59: Abacus mixed friends: plus 6
Level 5, Mix Mountain. What if the top bead is already down? Two moves you know do it.
What your child does, card by card
The mix: plus 6. 6 is 5 and 1. PlayType opens the lesson: “Now let's try a harder one.”
2 + 6 = 8: plus 6 is plus 5 and plus 1. The abacus makes 2, then clears. Here the hands lead: they show 2, 7 and 8, and a moment later the beads copy each one. “+5: the top bead”, “+1: one bead” and “= 8” glow on the card in step with the beads. The card ends on a touch: “Top bead down, then one bead up.”
6 + 5 = 11: top bead down already? Use the twins. The top beads are outlined in yellow while the kids explain. The beads show 6 and go back to zero. Here the hands lead: they show 6, 1 and 11, and a moment later the beads copy each one. Above, “−5: top bead off”, “+10: one ten on” and “= 11” take turns to glow. Its words: “The big friend of 5 is 5.”
7 + 6: the 1 fits. The 5 does not. A yellow line goes round the top beads as the kids name them. 7 appears on the beads, then the rod clears again. Here the hands lead: they show 7, and a moment later the beads copy it. The labels “Start at 7”, “+1: a bead is free” and “+5: no room” light up as each idea comes. “The top bead is down already.” Any bead or finger may be tapped afterwards.
+6 = +1 −5 +10: the 1 first. Then the 5, the twins' way. First the abacus shows the rule bead by bead (“+1: one bead”, “−5: the top bead” and “+10: one ten”). Next it is your child's turn: work out 7 + 6 and 5 + 6, the ring marking the top bead before the friend.
Try it puts a green ring on each next bead; your child works out 6 + 6, 8 + 6 and 15 + 6.
A tiny practice with no ring: work out 5 + 6, 9 + 6, 7 + 6, 3 + 6 and 18 + 6, each round starting from its own number.
In Copy me the drawn hand holds up 13, 11 and 12 in turn, and your child copies each one in beads.
In your head: the abacus is covered and your child works out 7 + 6, 5 + 6 and 8 + 6, showing each answer on the drawn fingers.
You're ready! Plus 6: one bead up, top bead off, one ten on.
What this lesson trains
16 answers, roughly five minutes: 34 moves of the beads, 9 of them with the top bead and 25 with bottom beads. Up to 24, read and set from the left. Then 3 quick looks in your head. Friends do 9 of the 10 sums, by +6 = +1 −5 +10 and +6 = −4 +10.
Your child’s first moves: work out 6 + 6, 8 + 6 and 15 + 6.
Fingers and hands
In the lower window two drawn hands work as a finger abacus and always match the beads: a finger up is a bottom bead (1), the thumb out is the top bead (5), a closed hand is zero. In this lesson the hands show zero and 1, 2, 3, 5, 6, 7, 8, 9, 11, 12, 13, 14, 15, 18, 21 and 24.
+6 on the fingers: the right hand opens one finger and folds the thumb, then the left hand opens one more finger for the ten (+1 −5 +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 “The mix: plus 6” 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.
The fingers lead in Copy me (13, 11 and 12); the beads answer.
What PlayBuddy and PlayType say
PlayType: “Six is five and one. So add five, then add one.”
PlayBuddy: “The big friend of five is five. They are twins.”
PlayType: “Big friend off, one ten on.”
PlayBuddy: “No room on this rod. Ask the big friend.”
Stars
Three stars for up to 1 slip in 16 answers, two stars for up to 4. A number counts as a slip only when it stays wrong for a moment and is not on the way to the answer, so a child who moves beads one at a time is never marked down. After two slips on one task the green ring comes back.
About Mix Mountain
Mix Mountain is Level 5 of nine (grade 2 to 3): small and big friends in one move, carries across several rods. In your head: mixed sums in your head.