How does a shadow change through the day?
- 🌳 Outside
- 😎 Never look at the sun
My hypothesis
If I change the time of day, then how long the shadow is will ______, because ______.
You fill in the blanks. Think about where the sun is in the sky at each time, and which way its light comes in. A guess is a good because: the test finds out.
Change, measure, keep the same
CHANGE
the time of day: 9 in the morning, Noon, 3 in the afternoon
MEASURE
how long the shadow is, in cm
KEEP THE SAME
- the same bottles in the same spots
- measuring from the bottom of each bottle
- a sunny day
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
- An empty plastic bottle: 3, the same size, filled with water
- Sidewalk chalk
- A tape measure, or a long ruler
Steps
- On a sunny morning, stand three bottles of water in a row on a path or driveway.
- Draw around the bottom of each bottle with chalk, so they always go back in the same place.
- At 9 o'clock, mark the tip of each bottle's shadow with chalk.
- Measure from each bottle to its mark, and write the numbers down.
- Do the same at noon and at 3 o'clock.
- Never look at the sun: look at the shadow on the ground.
- Draw a bar for each time of day. When was the shadow shortest?
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 does a shadow change through the day?
I changed: Time of day I measured: how long the shadow is (cm)
| Time of day | Try 1 (cm) | Try 2 (cm) | Try 3 (cm) | Mean |
|---|---|---|---|---|
| 9 in the morning | ||||
| Noon | ||||
| 3 in the afternoon |
MY GRAPH (a bar graph: time of day 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: How does a shadow change through the day?
If I change the time of day, then how long the shadow is will ________________, because _____________________________________________
| I CHANGE | I MEASURE | I KEEP THE SAME |
|---|---|---|
| Time of day: 9 in the morning, Noon, 3 in the afternoon | how long the shadow is (cm) |
|
What I think will happen, in my own words:
Name ______________________ Fair day ____________
Question: How does a shadow change through the day?
| Date | What I did | What I saw | What I think |
|---|---|---|---|
Name ______________________ Fair day ____________
Question: How does a shadow change through the day?
| Date | What I did | What I saw | What I think |
|---|---|---|---|
Name ______________________ Fair day ____________
Question: How does a shadow change through the day?
| Date | What I did | What I saw | What I think |
|---|---|---|---|
Name ______________________ Fair day ____________
Question: How does a shadow change through the day?
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: measure every hour from 9 to 3, and draw which way the shadow points at each time.
Why it works
A shadow is the dark patch where the bottle blocks the sunlight. In the morning and afternoon the sun is low in the sky, so its light comes in at a slant and the shadow stretches long. Around noon the sun is highest, so the shadow is shortest.
Going further (7th and up): Change a second thing: measure every hour from 9 to 3, and draw which way the shadow points at each time.
Board layout
- ❓ Question (10 × 8 in): How does a shadow change through the day?
- 💭 Hypothesis (10 × 9 in): If I change the time of day, then how long the shadow is will ______, because ______.
- 🧺 Materials (10 × 12 in): 3 things: see your list.
- 🪜 Steps (22 × 9 in): 7 steps, three tries at each level.
- 📊 Results (22 × 16 in): Your table (Time of day 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: An empty plastic bottle; Sidewalk chalk; A tape measure, or a long ruler.
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. |
From 4th grade up, the table gets a mean column. See every project for 1st grade, or print a blank results table.
What a judge will ask
- What did you change, and what did you measure? I changed the time of day and measured how long the shadow is, in cm.
- What did you keep the same, and why does that matter? I kept the same bottles in the same spots and measuring from the bottom of each bottle the same, so the only difference was the time of day.
- 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 measure every hour from 9 to 3, and draw which way the shadow points at each time.
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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