Does salty or sugary water change a bean plant?
- 👶 Small parts
- 🧼 Wash your hands after
- 🚫 Test food is not for eating
My hypothesis
If I change what the bean plants are watered with, then how tall the plant is on day 14 will ______, because ______.
You fill in the blanks. Think about how roots take in water, and what extra stuff dissolved in that water might do. A guess is a good because: the test finds out.
Change, measure, keep the same
CHANGE
what the bean plants are watered with: Plain tap water, Salty water, Sugary water
MEASURE
how tall the plant is on day 14, in cm
KEEP THE SAME
- the same kind of bean, soaked overnight
- the same cups, soil and amount of liquid
- the same bright windowsill
- watering on the same days
Scientists call the thing you change the independent variable and the thing you measure the dependent variable. The things you keep the same are the controls: if one of them changed too, you wouldn't know which change made the difference. Try each of the 3 levels 3 times.
What you need
- Dried beans from the grocery bag (pinto, lima or kidney): 18, all the same kind
- Paper cups with a hole poked in the bottom: 9, all the same
- Potting soil
- A baking tray or big plate: 1, to stand the cups on
- A clear jar or tall glass: 3, for the liquids
- Water from the tap
- Salt
- Sugar
- A measuring cup
- Measuring spoons
- Masking tape, to mark lines
- Crayons or markers
- ✂️ Kid scissors
- 📏 A ruler
Steps
- Soak 18 beans in a cup of water overnight.
- Fill nine cups with potting soil to 2 cm below the rim, and stand them on a tray.
- Push two beans a finger deep into each cup, and water each cup with a quarter cup of tap water.
- Every other day, water every cup with a quarter cup of tap water, until the shoots are up.
- Snip the smaller shoot in each cup off at the soil, so one plant is left.
- Pour 2 cups of tap water into each of three jars.
- Stir 1 teaspoon of salt into one jar and 1 teaspoon of sugar into another, and leave the third plain.
- Label the jars and the cups, so three cups are plain, three are salty and three are sugary.
- Every other day, water each cup with a quarter cup from its own jar, and mix fresh jars when they run low.
- Look at the leaves each week, and write down any that turn yellow or brown.
- On day 14, stand a ruler beside each plant and measure from the soil to its highest leaf tip.
- Write each height in your table, in centimetres.
- Find the mean height for each liquid and draw a bar graph.
- Pour away the leftover liquids, never drink them, and wash your hands after touching the soil.
Every step is one you can do yourself, with a grown-up nearby. Write each number down straight away, in the table below, so nothing is lost.
Your results table
Name ______________________ Fair day ____________
Question: Does salty or sugary water change a bean plant?
I changed: Watered with I measured: how tall the plant is on day 14 (cm)
| Watered with | Try 1 (cm) | Try 2 (cm) | Try 3 (cm) | Mean |
|---|---|---|---|---|
| Plain tap water | ||||
| Salty water | ||||
| Sugary water |
MY GRAPH (a bar graph: watered with along the bottom, cm up the side)
What I noticed: ______________________________________________
From 4th grade, add the tries for each level and divide by how many there were: that's the mean, and it goes in the last column. Then draw a bar graph, one bar for each thing you tried.
Name ______________________ Fair day ____________
Question: Does salty or sugary water change a bean plant?
If I change what the bean plants are watered with, then how tall the plant is on day 14 will ________________, because _____________________________________________
| I CHANGE | I MEASURE | I KEEP THE SAME |
|---|---|---|
| Watered with: Plain tap water, Salty water, Sugary water | how tall the plant is on day 14 (cm) |
|
What I think will happen, in my own words:
Name ______________________ Fair day ____________
Question: Does salty or sugary water change a bean plant?
| Date | What I did | What I saw | What I think |
|---|---|---|---|
Name ______________________ Fair day ____________
Question: Does salty or sugary water change a bean plant?
| Date | What I did | What I saw | What I think |
|---|---|---|---|
Name ______________________ Fair day ____________
Question: Does salty or sugary water change a bean plant?
| Date | What I did | What I saw | What I think |
|---|---|---|---|
Name ______________________ Fair day ____________
Question: Does salty or sugary water change a bean plant?
My hypothesis was ☐ right ☐ partly right ☐ not right.
I know because my numbers show:
What surprised me, or what might have gone wrong (7th and up):
Next time I would test:
Idea: Change a second thing: water with three amounts of salt, such as a quarter, a half and one teaspoon in 2 cups, and graph the height against the amount.
Why it works
A plant's roots pull in water, and the water carries minerals the plant needs. Too much salt in the soil makes it harder for roots to take water in, so a salty-watered plant is often shorter and its leaf edges may turn brown. A plant makes its own sugar in its leaves, so sugary water usually does not help it grow.
Going further (7th and up): Change a second thing: water with three amounts of salt, such as a quarter, a half and one teaspoon in 2 cups, and graph the height against the amount.
Board layout
- ❓ Question (10 × 8 in): Does salty or sugary water change a bean plant?
- 💭 Hypothesis (10 × 9 in): If I change what the bean plants are watered with, then how tall the plant is on day 14 will ______, because ______.
- 🧺 Materials (10 × 12 in): 12 things: see your list.
- 🪜 Steps (22 × 9 in): 14 steps, three tries at each level.
- 📊 Results (22 × 16 in): Your table (Watered with down the side, tries across) and your bar graph.
- ✅ Conclusion (10 × 14 in): My hypothesis was right / partly right / not right. I know because…
Materials to list: Dried beans from the grocery bag (pinto, lima or kidney); Paper cups with a hole poked in the bottom; Potting soil; A baking tray or big plate; A clear jar or tall glass; Water from the tap; Salt; Sugar; A measuring cup; Measuring spoons; Masking tape, to mark lines; Crayons or markers.
Bring photos or drawings of your test. Nothing wet, hot, powered or alive on the table.
This project at your grade
| 4th–6th grade | Tries: three at each level. The table: units in the header and a mean column. The graph: a bar graph, or a line for a number that grows. The conclusion: right, partly or not, and the numbers that show it. |
|---|---|
| 7th grade and up | Tries: three or more at each level. The table: a mean for every level of both tests. The graph: a graph with two lines or two sets of bars. The conclusion: the numbers, what might have gone wrong, and a next question. Second variable: water with three amounts of salt, such as a quarter, a half and one teaspoon in 2 cups, and graph the height against the amount. |
Every grade this project fits works out a mean. See every project for 4th grade, or print a blank results table.
What a judge will ask
- What did you change, and what did you measure? I changed what the bean plants are watered with and measured how tall the plant is on day 14, in cm.
- What did you keep the same, and why does that matter? I kept the same kind of bean, soaked overnight and the same cups, soil and amount of liquid the same, so the only difference was what the bean plants are watered with.
- How many times did you test it? 3 times at each of my 3 levels.
- If you did it again, what would you change or test next? I'd water with three amounts of salt, such as a quarter, a half and one teaspoon in 2 cups, and graph the height against the amount.
Make it yours
Keep this project on this device and Peabody counts down to your fair day, with a plan for each day. Nothing is sent anywhere.
Try next
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