Comparisons I am learning to add and subtract using comparisons of sets without counting down or counting up. 9, 8, 7, 6… 3, 4, 5, 6… Looking at one group and another group at the same time.
Tim has 5 counters and Kate has 8 counters. How many more counters does Kate have than Tim? First line up 5 counters for Tim. You might like to do this with your own counters. Now line up Kate’s counters underneath these. Tip: Make sure they are lined up right underneath each other. You can see that Kate has 3 more counters than Tim. Kate’s counters Tim’s counters We can record this as either; 8 – 5 = 3 or 5 + 3 = 8 Kate has this many more counters than Tim.
Zac has 12 counters and Amy has 7 counters. How many more counters does Zac have than Amy? First line up 12 counters for Zac. You might like to do this with your own counters. Now line up Amy’s counters underneath these. You can see that Zac has 5 more counters than Amy. We can record this as either; Amy’s counters Zac’s counters Note how we have worked out the answer to this question without having to count up or count down. Instead we used comparisons. 12 – 7 = 5 or 7 + 5 = 12 Zac has this many more counters than Amy.
Now lets try one together. Craig has 11 counters and Courtney has 8 counters. How many more counters does Craig have. Step 1: Imagine Craig’s counters lines up in your head. Step 2: Imagine Courtney’s counters lined up directly below these. Step 3: How many more counters does Craig have than Courtney? Is this what you imagined in your head? Craig: Courtney: Step 4: What number fits in the gaps below to answer the question? 3 3 11 - ….. = 8 8 + …..= 11
Now try these questions on your own. Remember to imagine the two amounts lined up and compare them to find your answer. Click again when you have worked out all your answers. 1) Andrew has 15 counters and Nicola has 9 counters. How many more counters does Andrew have? 9 + …… = 15 or 15 – 9 = ………. 2) Tara has 13 counters and Callum has 7 counters. How many more counters does Tara have? 7 + …… = 13 or 13 – 7 = ………. 2) Sophie has 19 counters and Josh has 15 counters. How many more counters does Sophie have? 15 + …… = 19 or 19 – 15 = ………. 6 6 6 6 4 4 Need some more practise? Try Pg41 of Teacher Tools Addition and Subtraction Book Numeracy resources