📈 Bars or a line?

The answers, and why

1. Bouncing balls on different floors: you tried "Carpet", "Hard floor (wood or tile)" and "A folded towel", and measured how high the ball bounces. Which graph should you draw? A bar graph. Yes. "Carpet", "Hard floor (wood or tile)" and "A folded towel": each one is its own thing to compare, so each gets its own bar. Bars are for separate things.

2. Pendulum length and swings: you tried "20 cm", "40 cm" and "60 cm", and measured how many swings it makes in 15 seconds. Which graph should you draw? A line graph. Yes. The levels go up in steps, from "20 cm" to "60 cm", so the dots join up into a line that shows the pattern. A line is for a number that grows.

3. Melting ice with salt, sugar and sand: you tried "Nothing", "Salt", "Sugar" and "Sand", and measured how long the ice cube takes to melt. Which graph should you draw? A bar graph. Yes. "Nothing", "Salt", "Sugar" and "Sand": each one is its own thing to compare, so each gets its own bar. Bars are for separate things.

4. Marble run height and speed: you tried "40 cm", "80 cm" and "120 cm", and measured how fast the marble crosses 2 m of floor. Which graph should you draw? A line graph. Yes. The levels go up in steps, from "40 cm" to "120 cm", so the dots join up into a line that shows the pattern. A line is for a number that grows.

5. Bean seeds and water: you tried "None", "A little (1 teaspoon)", "Medium (1 tablespoon)" and "Lots (3 tablespoons)", and measured how many of the five beans sprout in ten days. Which graph should you draw? A bar graph. Yes. "None", "A little (1 teaspoon)", "Medium (1 tablespoon)" and "Lots (3 tablespoons)": each one is its own thing to compare, so each gets its own bar. Bars are for separate things.

6. Water temperature and spreading colour: you tried "Cold from the fridge", "Room temperature" and "Hot, poured by a grown-up", and measured how long one drop of colour takes to spread through the whole cup. Which graph should you draw? A line graph. Yes. The levels go up in steps, from "Cold from the fridge" to "Hot, poured by a grown-up", so the dots join up into a line that shows the pattern. A line is for a number that grows.

7. Coloured paper in the sun: you tried "White", "Yellow", "Blue" and "Black", and measured how many degrees the thermometer under the paper warms in 20 minutes. Which graph should you draw? A bar graph. Yes. "White", "Yellow", "Blue" and "Black": each one is its own thing to compare, so each gets its own bar. Bars are for separate things.

8. Ball drop height and bounce: you tried "25 cm", "50 cm", "75 cm" and "100 cm", and measured how high the ball bounces. Which graph should you draw? A line graph. Yes. The levels go up in steps, from "25 cm" to "100 cm", so the dots join up into a line that shows the pattern. A line is for a number that grows.