What is on this worksheet
Bonds to twenty are where the work done on bonds to ten pays off. Faced with a whole of twenty and a part of thirteen, a child who knows their bonds to ten can go from thirteen to twenty in one jump instead of counting seven times. The wholes on this sheet vary rather than sitting at twenty every time, so the whole has to be read on each diagram rather than assumed, which catches children who have started answering on autopilot.
How to use it
Print the sheet and fill the empty circle so the two parts add up to the whole above them. Wholes here sit at or just below twenty rather than always at ten.
Three ways to practice
Bridge through the nearest ten
Work out how far the given part is from ten or twenty first, then finish. Turning one hard step into two easy ones is the strategy worth teaching here, not a faster count.
Check by adding back
After writing the missing part, add the two parts together and compare with the whole. Checking is a habit, and a bond diagram makes it quick enough that a child will actually do it.
Write the four facts
Every bond holds two additions and two subtractions. Writing all four next to one diagram shows how much a single bond is carrying and cuts the number of facts to memorize.
A tip worth knowing
Bridge through ten. To find what goes with thirteen to make twenty, get to twenty from thirteen by adding seven to reach twenty. Bonds to ten are the tool that makes bonds to twenty quick.
Printing this sheet
Frequently asked questions
Do the wholes change on this sheet?
Yes. They sit at or just below twenty rather than being twenty every time, so your child has to read the whole on each diagram instead of assuming it. That small change catches automatic answering.
Should bonds to ten come first?
Almost always. Bonds to twenty are much faster for a child who can already bridge through ten, and much slower for one who cannot. If these feel hard, go back a sheet.
How many should we do in one sitting?
A few minutes is enough. Short frequent practice builds recall better than a long session, and a child who is still counting every one by the end of a page is tired rather than learning.