Fact Families



today's lesson is all about a fact family a fact family contains three numbers that all work together with those three numbers we can come up with two addition problems and two subtraction problems if this was our fact house I see I'm using the numbers two six and four these are the only three numbers that we can use to come up with two addition problems and two subtraction problems well I know that when I write an addition problem the largest number is going to be the answer so if I'm using the numbers 2 4 & 6 the largest number is 6 so for an addition problem the six will be my answer so the answer is 6 this addition problem the answer is 6 well I've used the six the only two numbers I can use now are the 2 and the 4 so I'm going to put the 2 in here and the four and here now I have an addition sentence 2 plus 4 equals 6 well we've been talking about flip-flop or turnaround facts I know I can flip around the 2 and the 4 and get the same answer so instead of writing a tool here I'm going to flip it with the 4 instead of writing a 4 here I'm going to flip it with the 2 so my new addition sentence says 4 plus 2 equals 6 great we have our 2 addition problems now we need two subtraction problems when I write a subtraction problem the largest number always comes first well the 6 is the largest number so that's going to come first right it in both of the subtraction problems the largest number first well I've used the six so I only have the two and the four left to use well I'm going to put the two here six minus two equals the other number that's left your right is a four and if I try it six minus two yes you're right the answer is four well I have one more subtraction problem remember I can only use these three numbers six – I've already subtracted two so this time let's subtract four six minus four equals what number haven't we used you're right the – this is a fact family – addition problems and two subtraction problems using the same three numbers great job let's take a look at another one in this fact family we have the three numbers of two five and three let's start with our two addition problems well remember from the last fact family we said the largest number in an addition problem will be the answer what number is the largest of these three you're right it's the five so let's write the five as our answer we've used the five so we have the two and the three let's add those together two plus three does it equal five yes it does well let's flip-flop these two numbers to make the second addition problem instead of two plus three let's flip it around three plus two is three plus two equal five yes it does great job now now let's make the two subtraction problems well before we said the largest number needs to go in front of a subtraction problem so let's put the five because that's the largest number out front and the other two numbers we can use are either the two or the three well let's put the two in now our number sentence is five minus two equals you got it three and the last subtraction problem five – well we already subtracted two so this time let's subtract three five minus three equals what number haven't we used you're right the two now there's lots of different ways to write a fact family this is one way kind of looks like a house sometimes we can write them using a domino up here this is where we're going to write the three numbers we're going to use so if I look at this Domino on the top there are two dots so two is one of the numbers we're going to use I look on the bottom there are four dots four is the number we're going to use in our fact family and all together I have one two three four five six six is a member of our fact family now remember I need to addition problems and to subtraction problems let's start with addition well I know the largest number in an addition problem is the answer 2 4 6 the largest number is 6 so that's going to be the answer now we have a 2 + 4 2 + 4 equals 6 now you know what I know about flip flop facts let's flip these two numbers around instead of a 2 let's put a 4 4 plus 2 equals 6 now that we have our two addition problems let's write our two subtraction problems I remember and a subtraction problem the largest number goes first so I'm going to put the six out front six – now remember these are the only numbers I can use let's start with the two six minus two equals what number haven't I used yet you're right the four six minus two equals four great job let's write the last subtraction problem six – I can't subtract two again so this time let's put the four there six minus four equals you're right – great job so we can write fact families like this using a domino another way you might see a fact family is a fact family triangle and if you look at this triangle again you see three numbers on the top is usually the biggest number and I know this is the top of the triangle because there's a dot there that is the largest number so using these three numbers 5 3 & 8 could you write the members of the fact family the two addition problems and the two subtraction problems on your whiteboard so pause the video write your two addition problems and two subtraction problems once you're finished hit the play button and check your answers all right let's check your work one of the addition problems could be five plus three equals eight the other audition problem is the flip flop fact 3 plus 5 equals 8 how'd you do did you have those two addition problems let's check the subtraction problems well I remember on a subtraction problem the largest number goes first well that's the 8 8 – I'm going to start with using the 3 8 minus 3 equals what number is left you're right the 5 8 minus 3 equals 5 and the last subtraction problem I always start with the largest number the 8 I can't use the 3 again I've already subtracted 3 this time I'm going to subtract 5 8 minus 5 equals what number is left I've used the 8 I've used the 5 the 3 is left 8 minus 5 equals 3 how'd you do let's try one more this time the members we have a 5 a 2 and a 3 why don't you pause the video write the 2 addition problems and the 2 subtraction problems on your whiteboard and then play the video to check your work are you ready to check your work alright let's start with our two addition problems I remember that the largest number which is a 5 needs to be the answer of an addition problem so I'm going to write the 5 here now I'm going to use the two other numbers I'm going to put the three here plus two so I have three plus two equals five great job now I'm going to write the flip flop fact instead of a three I'm going to flip it with the two instead of the two I'm going to flip it with the three we can flip flop the numbers and still get the same answer how'd you do with your addition sentences three plus two equals five and two plus three equals five let's write our two subtraction problems remember with subtraction the largest number goes first which is a five in this case five – let's take the two five minus two equals you're right the three is left five minus two equals three and the last subtraction problem five – I can't subtract the two again so I'll have to subtract three five minus three equals your right to check your work how'd you do great job everyone that's the end of our lesson all about fact families

27 thoughts on “Fact Families

  1. my mom is letting me do math facts all the time I hate doing this I Arley know how to do this all ready so I've had get a hunnyboo that mean we have r get a pet that is all u have to say bye guys and fana

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