How much salt does it take to float an egg?
- 🧼 Wash your hands after
- 🚫 Test food is not for eating
My hypothesis
If I change how much salt is in the water, then how high the top of the egg sits in the glass will ______, because ______.
You fill in the blanks. Think about whether salt water feels heavier than the same amount of plain water. A guess is a good because: the test finds out.
Change, measure, keep the same
CHANGE
how much salt is in the water: 0 tablespoons, 2 tablespoons, 4 tablespoons, 6 tablespoons, 8 tablespoons
MEASURE
how high the top of the egg sits in the glass, in cm
KEEP THE SAME
- the same egg
- the same 2 cups of water
- stirring until the salt disappears
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 5 levels 3 times.
What you need
- Eggs: 1 raw egg
- Salt: about half a cup
- Water from the tap
- A measuring cup
- Measuring spoons
- A clear jar or tall glass: a tall clear glass
- A spoon
- 📏 A ruler
Steps
- Pour 2 cups of water into a tall clear glass.
- Lower the egg in gently with a spoon, and measure how high its top is.
- Lift the egg out and stir in 2 tablespoons of salt until it disappears.
- Lower the egg in again and measure.
- Keep going, 2 more tablespoons at a time, until you've added 8.
- Pour it out and do the whole test two more times.
- Wash your hands after touching the raw egg.
- Draw a line graph: salt along the bottom, egg height up the side.
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: How much salt does it take to float an egg?
I changed: Tablespoons of salt in 2 cups of water I measured: how high the top of the egg sits in the glass (cm)
| Tablespoons of salt in 2 cups of water | Try 1 (cm) | Try 2 (cm) | Try 3 (cm) | Mean |
|---|---|---|---|---|
| 0 tablespoons | ||||
| 2 tablespoons | ||||
| 4 tablespoons | ||||
| 6 tablespoons | ||||
| 8 tablespoons |
MY GRAPH (a line graph: tablespoons of salt in 2 cups of water 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 line graph, because the thing you change is a number that goes up.
Name ______________________ Fair day ____________
Question: How much salt does it take to float an egg?
If I change how much salt is in the water, then how high the top of the egg sits in the glass will ________________, because _____________________________________________
| I CHANGE | I MEASURE | I KEEP THE SAME |
|---|---|---|
| Tablespoons of salt in 2 cups of water: 0 tablespoons, 2 tablespoons, 4 tablespoons, 6 tablespoons, 8 tablespoons | how high the top of the egg sits in the glass (cm) |
|
What I think will happen, in my own words:
Name ______________________ Fair day ____________
Question: How much salt does it take to float an egg?
| Date | What I did | What I saw | What I think |
|---|---|---|---|
Name ______________________ Fair day ____________
Question: How much salt does it take to float an egg?
| Date | What I did | What I saw | What I think |
|---|---|---|---|
Name ______________________ Fair day ____________
Question: How much salt does it take to float an egg?
| Date | What I did | What I saw | What I think |
|---|---|---|---|
Name ______________________ Fair day ____________
Question: How much salt does it take to float an egg?
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: try sugar instead of salt, spoon for spoon, and draw both lines on one graph.
Why it works
Salt water is heavier than the same amount of plain water, which scientists call denser. An egg sinks in plain water because the egg is denser than the water. Once enough salt dissolves, the water becomes denser than the egg and pushes it up.
Going further (7th and up): Change a second thing: try sugar instead of salt, spoon for spoon, and draw both lines on one graph.
Board layout
- ❓ Question (10 × 8 in): How much salt does it take to float an egg?
- 💭 Hypothesis (10 × 9 in): If I change how much salt is in the water, then how high the top of the egg sits in the glass will ______, because ______.
- 🧺 Materials (10 × 12 in): 7 things: see your list.
- 🪜 Steps (22 × 9 in): 8 steps, three tries at each level.
- 📊 Results (22 × 16 in): Your table (Tablespoons of salt in 2 cups of water down the side, tries across) and your line graph.
- ✅ Conclusion (10 × 14 in): My hypothesis was right / partly right / not right. I know because…
Materials to list: Eggs; Salt; Water from the tap; A measuring cup; Measuring spoons; A clear jar or tall glass; A spoon.
Bring photos or drawings of your test. Nothing wet, hot, powered or alive on the table.
This project at your grade
| 1st–3rd grade | Tries: three at each level (one is fine at a first fair). The table: levels and tries, numbers or pictures. The graph: a picture, or a simple bar graph. The conclusion: what happened, in their words. |
|---|---|
| 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: try sugar instead of salt, spoon for spoon, and draw both lines on one graph. |
From 4th grade up, the table gets a mean column. See every project for 3rd grade, or print a blank results table.
What a judge will ask
- What did you change, and what did you measure? I changed how much salt is in the water and measured how high the top of the egg sits in the glass, in cm.
- What did you keep the same, and why does that matter? I kept the same egg and the same 2 cups of water the same, so the only difference was how much salt is in the water.
- How many times did you test it? 3 times at each of my 5 levels.
- If you did it again, what would you change or test next? I'd try sugar instead of salt, spoon for spoon, and draw both lines on one graph.
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
👨👩👧 For grown-ups and teachers: how much to help, the safety rules, and running a school fair. Science fair v0.16.1 · Checked .