### Video Transcript

Find the missing addition
sentence. Nine plus zero is nine. Eight plus one is nine. Seven plus two is nine. Six plus three is nine. Five plus four is nine. What plus what is nine. Three plus six is nine. Two plus seven is nine. And one plus eight is nine.

The model shows all the number
bonds to nine. The pictures use blue and green
tennis balls to model the addition expressions. Let’s look more closely at the
strategy that’s been used to find the pairs. In other words, let’s look
closely at the numbers in the number bonds. Let’s see if we can spot any
patterns.

Nine blue tennis balls and no
green tennis balls makes nine. Eight and one is nine. Seven and two is nine. Six and three is nine. Five plus four is nine. Have you spotted the pattern
yet? Did you notice what’s happening
to the number of blue balls each time? Nine, eight, seven, six,
five. The numbers are decreasing. The number of blue balls is
going down. There’s one less blue ball each
time. Which number would come
next? Nine, eight, seven, six, five,
four.

Now we need to work out the
number of green balls. Let’s see if we can spot the
pattern. Zero, one, two, three, four,
five. The number of green balls
increases by one each time. We’re adding one green ball
each time. The missing addition sentence
is four plus five is nine.

We found the missing addition
sentence by looking closely at what happened to the number of blue and green
balls each time. We could use the model to help
us check the answer. Are there four blue balls? One, two, three, four. Yes, there are. Let’s check there are five
green balls. One, two, three, four,
five. Four plus five is nine.