Does a bigger water drop make letters look bigger?
- 💧 Water
My hypothesis
If I change how big the water drop is, then how tall a letter looks through the drop will ______, because ______.
You fill in the blanks. Think about the shape of the top of each drop, and how a magnifying glass is shaped. A guess is a good because: the test finds out.
Change, measure, keep the same
CHANGE
how big the water drop is: No water, 1 drop, 4 drops, 10 drops
MEASURE
how tall a letter looks through the drop, in mm
KEEP THE SAME
- the same letter in the same size of print
- the same plastic wrap, lying flat
- looking straight down from the same height
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 4 levels 3 times.
What you need
- Clear plastic wrap
- Paper: a page of small printed words
- Straws: 1, for a dropper
- Water from the tap
- 🩹 Tape
- 📏 A ruler
Steps
- Find a page of small print and pick a letter it has lots of, like e.
- Lay plastic wrap flat over the page and tape its edges down.
- With no water on them, measure how tall three of your letters are in mm, a ruler laid beside each.
- Dip a straw in water, cover its top with a finger, and let one drop fall on another of your letters.
- Look straight down and measure how tall the letter looks, with the ruler beside the drop.
- Do the same with single drops on two more of the same letter.
- Do three tries with 4 drops in one blob, and three with 10 drops.
- Find the mean for each size and draw a line graph.
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 a bigger water drop make letters look bigger?
I changed: Drop size I measured: how tall a letter looks through the drop (mm)
| Drop size | Try 1 (mm) | Try 2 (mm) | Try 3 (mm) | Mean |
|---|---|---|---|---|
| No water | ||||
| 1 drop | ||||
| 4 drops | ||||
| 10 drops |
MY GRAPH (a line graph: drop size along the bottom, mm 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: Does a bigger water drop make letters look bigger?
If I change how big the water drop is, then how tall a letter looks through the drop will ________________, because _____________________________________________
| I CHANGE | I MEASURE | I KEEP THE SAME |
|---|---|---|
| Drop size: No water, 1 drop, 4 drops, 10 drops | how tall a letter looks through the drop (mm) |
|
What I think will happen, in my own words:
Name ______________________ Fair day ____________
Question: Does a bigger water drop make letters look bigger?
| Date | What I did | What I saw | What I think |
|---|---|---|---|
Name ______________________ Fair day ____________
Question: Does a bigger water drop make letters look bigger?
| Date | What I did | What I saw | What I think |
|---|---|---|---|
Name ______________________ Fair day ____________
Question: Does a bigger water drop make letters look bigger?
| Date | What I did | What I saw | What I think |
|---|---|---|---|
Name ______________________ Fair day ____________
Question: Does a bigger water drop make letters look bigger?
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: lift the plastic wrap 1 cm and 2 cm above the page on stacks of pennies, and draw a line for each height.
Why it works
A water drop has a curved top, like a magnifying glass, and a curved top bends light so things under it look bigger. A small drop is rounder, so it usually bends light more. A big drop sags flat in the middle, and a flat top hardly bends light at all.
Going further (7th and up): Change a second thing: lift the plastic wrap 1 cm and 2 cm above the page on stacks of pennies, and draw a line for each height.
Board layout
- ❓ Question (10 × 8 in): Does a bigger water drop make letters look bigger?
- 💭 Hypothesis (10 × 9 in): If I change how big the water drop is, then how tall a letter looks through the drop will ______, because ______.
- 🧺 Materials (10 × 12 in): 4 things: see your list.
- 🪜 Steps (22 × 9 in): 8 steps, three tries at each level.
- 📊 Results (22 × 16 in): Your table (Drop size 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: Clear plastic wrap; Paper; Straws; Water from the tap.
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: lift the plastic wrap 1 cm and 2 cm above the page on stacks of pennies, and draw a line for each height. |
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 how big the water drop is and measured how tall a letter looks through the drop, in mm.
- What did you keep the same, and why does that matter? I kept the same letter in the same size of print and the same plastic wrap, lying flat the same, so the only difference was how big the water drop is.
- How many times did you test it? 3 times at each of my 4 levels.
- If you did it again, what would you change or test next? I'd lift the plastic wrap 1 cm and 2 cm above the page on stacks of pennies, and draw a line for each height.
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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