Year 2: Sorting and counting into groups
Part of the Year 2 statistics chapter. Chapter overview · whole chapter on one page
Sorting and counting into groups
We can sort things into groups. Each group holds one kind of thing.
To find out how many are in a group, we count it. Touch each one once as you count.
When we know every count, we can compare them. We can say which group has the most. We can also say which group has the fewest.
Key ideas
- A group holds one kind of thing.
- Count each object once, and only once.
- The group with the most objects has the most.
- Put the groups in order, from fewest to most, using the counts.
Method. Count the coats once each, touching each one.
- Touch each one once. Say the number as you touch each one.1 2 3 4 5 6
- Read the last number. The last number is how many there are.6
- Write the answer. 6
Check. Count them again from the other end. You get 6 again. ✓
Watch out. Move each one to one side as you count it, so you do not count it twice.
Method. Compare the counts. The smallest count is the fewest.
- Write down each count. Put each count next to its name.hats 3, coats 6, socks 4
- Find the smallest count. 3 is the smallest count.smallest: 3
- Write the answer. The hats row has 3.hats
Check. Every other count is bigger than 3. ✓
Watch out. Check every count, not only the first two. The fewest is the count that is smaller than all the others.
Method. Find each count, then put the rows in order of their counts, fewest first.
- Write down each count. Put each count next to its name.hats 3, coats 6, socks 4
- Put the counts in order, fewest first. Start from the smallest count.3 → 4 → 6
- Write the order. hats, socks, coats
Check. Check that each count is bigger than the one before it. ✓
Watch out. Compare the counts, not the names. The longest name does not mean the biggest count.
Watch out
Watch out: a group that looks big may have fewer objects. Count every one before you compare.
Exam tip
Grown-up tip. Put out about 20 buttons or coins in small piles. Ask: “How many in this pile?” Then ask: “Which pile has the most? Which has the fewest?”
Exercise 10A Sorting and counting into groups
Non-calculatorMethod. Count the balls once each, touching each one.
- Touch each one once. Say the number as you touch each one.1 2 3 4 5
- Read the last number. The last number is how many there are.5
- Write the answer. 5
Check. Count them again from the other end. You get 5 again. ✓
Watch out. Move each one to one side as you count it, so you do not count it twice.
Method. Count the teddy bears once each, touching each one.
- Touch each one once. Say the number as you touch each one.1 2
- Read the last number. The last number is how many there are.2
- Write the answer. 2
Check. Count them again from the other end. You get 2 again. ✓
Watch out. Move each one to one side as you count it, so you do not count it twice.
Method. Count the kites once each, touching each one.
- Touch each one once. Say the number as you touch each one.1 2 3 4 5 6 7
- Read the last number. The last number is how many there are.7
- Write the answer. 7
Check. Count them again from the other end. You get 7 again. ✓
Watch out. Move each one to one side as you count it, so you do not count it twice.
Method. Count the cars once each, touching each one.
- Touch each one once. Say the number as you touch each one.1 2 3 4
- Read the last number. The last number is how many there are.4
- Write the answer. 4
Check. Count them again from the other end. You get 4 again. ✓
Watch out. Move each one to one side as you count it, so you do not count it twice.
Method. Compare the counts. The biggest count is the most.
- Write down each count. Put each count next to its name.balls 5, teddy bears 2, kites 7, cars 4
- Find the biggest count. 7 is the biggest count.biggest: 7
- Write the answer. The kites row has 7.kites
Check. Every other count is smaller than 7. ✓
Watch out. Check every count, not only the first two. The most is the count that is bigger than all the others.
Method. Compare the counts. The smallest count is the fewest.
- Write down each count. Put each count next to its name.balls 5, teddy bears 2, kites 7, cars 4
- Find the smallest count. 2 is the smallest count.smallest: 2
- Write the answer. The teddy bears row has 2.teddy bears
Check. Every other count is bigger than 2. ✓
Watch out. Check every count, not only the first two. The fewest is the count that is smaller than all the others.
Method. Find each count. Then take the smaller count away from the bigger one.
- Count the kites. There are 7.kites: 7
- Count the cars. There are 4.cars: 4
- Take the smaller count away from the bigger one. The difference is how many more or fewer.7 - 4 = 3
- Write the answer. 3
Check. Add the difference back on: 4 + 3 = 7. ✓
Watch out. Take away the smaller number from the bigger one. Do not add them.
Method. Find each count. Then take the smaller count away from the bigger one.
- Count the balls. There are 5.balls: 5
- Count the teddy bears. There are 2.teddy bears: 2
- Take the smaller count away from the bigger one. The difference is how many more or fewer.5 - 2 = 3
- Write the answer. 3
Check. Add the difference back on: 2 + 3 = 5. ✓
Watch out. Take away the smaller number from the bigger one. Do not add them.
Method. Find each count, then put the rows in order of their counts, fewest first.
- Write down each count. Put each count next to its name.balls 5, teddy bears 2, kites 7, cars 4
- Put the counts in order, fewest first. Start from the smallest count.2 → 4 → 5 → 7
- Write the order. teddy bears, cars, balls, kites
Check. Check that each count is bigger than the one before it. ✓
Watch out. Compare the counts, not the names. The longest name does not mean the biggest count.
Method. Find each count, then add them all together.
- Write down each count. Each count is one row.teddy bears 2, kites 7
- Add the counts together. Add them all, so none is missed.2 + 7 = 9
- Write the answer. 9
Check. Add them in the other order to check: 7 + 2 = 9. ✓
Watch out. Make sure every row is in your total, and no row is counted twice.
Method. Take the 2 away from the kites, then compare with the cars.
- Count the kites. There are 7.kites: 7
- Take 2 away. 7 - 2 = 5.7 - 2 = 5
- Compare with the cars. There are 4 cars.5 and 4 are different
- Decide. Is Ali right?No
Check. Count the kites again after taking 2 away, to check: 5. ✓
Watch out. Take the number away first. Then compare the two numbers.