Year 2: Block diagrams
Part of the Year 2 statistics chapter. Chapter overview · whole chapter on one page
Block diagrams
A block diagram uses blocks to show counts. Each block stands for one thing.
Each colour has its own column. Count the blocks in a column to find its count.
The tallest column has the most blocks. The shortest column has the fewest.
Key ideas
- Each block stands for one thing.
- Count the blocks in one column.
- The tallest column has the most blocks.
- Add two counts together to find how many altogether.
Method. Count the pink blocks 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. Find each count, then add them all together.
- Write down each count. Each count is one row.pink 6, green 2, orange 5
- Add the counts together. Add them all, so none is missed.6 + 2 + 5 = 13
- Write the answer. 13
Check. Add them in the other order to check: 5 + 2 + 6 = 13. ✓
Watch out. Make sure every row is in your total, and no row is counted twice.
Method. Compare the counts. The smallest count is the fewest.
- Write down each count. Put each count next to its name.pink 6, green 2, orange 5
- Find the smallest count. 2 is the smallest count.smallest: 2
- Write the answer. The green row has 2.green
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.
Watch out
Watch out: read the label under each column before you count it. The label tells you the colour.
Exam tip
Grown-up tip. Stack coloured bricks, sweets or cubes in columns, one column for each colour. Ask: “How many in the red column? Which column is the tallest?”
Exercise 10D Block diagrams
Non-calculatorMethod. Count the red blocks 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. Count the blue blocks 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 yellow blocks once each, touching each one.
- Touch each one once. Say the number as you touch each one.1 2 3
- Read the last number. The last number is how many there are.3
- Write the answer. 3
Check. Count them again from the other end. You get 3 again. ✓
Watch out. Move each one to one side as you count it, so you do not count it twice.
Method. Count the green blocks 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. Compare the counts. The biggest count is the most.
- Write down each count. Put each count next to its name.red 4, blue 7, yellow 3, green 5
- Find the biggest count. 7 is the biggest count.biggest: 7
- Write the answer. The blue row has 7.blue
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.red 4, blue 7, yellow 3, green 5
- Find the smallest count. 3 is the smallest count.smallest: 3
- Write the answer. The yellow row has 3.yellow
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 add them all together.
- Write down each count. Each count is one row.red 4, blue 7, yellow 3, green 5
- Add the counts together. Add them all, so none is missed.4 + 7 + 3 + 5 = 19
- Write the answer. 19
Check. Add them in the other order to check: 5 + 3 + 7 + 4 = 19. ✓
Watch out. Make sure every row is in your total, and no row is counted twice.
Method. Find each count. Then take the smaller count away from the bigger one.
- Count the blue. There are 7.blue: 7
- Count the red. There are 4.red: 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 add them all together.
- Write down each count. Each count is one row.blue 7, yellow 3
- Add the counts together. Add them all, so none is missed.7 + 3 = 10
- Write the answer. 10
Check. Add them in the other order to check: 3 + 7 = 10. ✓
Watch out. Make sure every row is in your total, and no row is counted twice.
Method. Find each count, then put the rows in order of their counts, most first.
- Write down each count. Put each count next to its name.red 4, blue 7, yellow 3, green 5
- Put the counts in order, most first. Start from the biggest count.7 → 5 → 4 → 3
- Write the order. blue, green, red, yellow
Check. Check that each count is smaller than the one before it. ✓
Watch out. Compare the counts, not the names. The longest name does not mean the biggest count.
Method. Take the 2 away from the blue, then compare with the green.
- Count the blue. There are 7.blue: 7
- Take 2 away. 7 - 2 = 5.7 - 2 = 5
- Compare with the green. There are 5 green.5 and 5 are the same
- Decide. Is Ali right?Yes
Check. Count the blue again after taking 2 away, to check: 5. ✓
Watch out. Take the number away first. Then compare the two numbers.