Number Bonds Board

About this tool

Number Bonds Board is the whole-and-parts instrument, on the projector. A number sits in the nest at the top; underneath it two trays hold the parts. A child takes one counter from a tray and carries it across, and the two parts change while the number in the nest does not. That is the whole lesson, and it is built into the material rather than written on it: there is no way to add a counter and no way to remove one, so the parts cannot stop adding up to the whole.

Turn on two colours and the board makes the bond visible. The left part wears one colour, the right part the other, and the nest shows them as one unbroken run — so a carry does not lengthen or shorten that run, it changes exactly one counter’s coat. A double reads as one full row of each colour. Nothing is marked and nothing is scored, because every split of a number is correct: six is four and two, and it is also five and one, and a child moving counters back and forth is finding out that a number is made of smaller numbers.

A cloth covers the nest or either tray, which turns the same board into the three questions teachers actually ask: how many altogether, and how many are hiding. While a cloth is down the board goes quiet everywhere — the numeral, the spoken split and the record all stop giving the answer away. Numbers to ten, all three cloths, four counter shapes, three colour schemes, the spoken split and the written form are free. Numbers to twenty, the record of every way a class has found, and the two-page printable are part of the Teacher plan.

How to use it in class

• Put the board on the projector and set today’s number with the plus and minus buttons, or tap five, ten or twenty.
• Ask a child to come up and tap a tray. One counter crosses over; tapping is the same as dragging, so it works on a board or a tablet.
• Say the split out loud together each time: six is four and two. Turn on Say the split aloud and the board says it with you, in your language.
• Cover a tray and ask how many are hiding. Cover the nest instead and ask how many there are altogether — nothing on the board will answer for them.
• Turn on the written form when you want the number sentence beside the counters, or all four facts when the class is ready for them.

Classroom ideas

• Fix the number for a whole week. Monday is six, and every morning a different child finds a different way to make six.
• Switch on two colours and ask what changed after a carry. The row up top is the same length; one counter changed colour. That is conservation, and they can see it.
• Cover one tray before the child carries a counter across, so the class has to work out what changed without seeing it.
• Print the mat, hand out real counters, and let them do on the carpet what you did on the board.