Science Fair

Grown-ups

Does slanted light spread wider?

5th–8th grade · 1 day of testing · about $1 · ages 10 to 14 · 45 minutes a sitting

  • 🙅 Never at faces
What you need for the slanted light and spot size project: a flashlight, paper, a protractor, a pencil, masking tape, to mark lines

My hypothesis

If I change the angle the light hits the paper, then how many squares of the grid the light covers will ______, because ______.

You fill in the blanks. Think about what happens to a patch of light when it lands on a surface at a slant instead of straight on. A guess is a good because: the test finds out.

Change, measure, keep the same

CHANGE

the angle the light hits the paper: 90 degrees (straight down), 60 degrees, 30 degrees

MEASURE

how many squares of the grid the light covers, in squares

KEEP THE SAME

  • the same flashlight
  • its glass the same distance from the dot each time
  • aiming at the same dot
  • the same dim room, counting squares more than half lit

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

  • A flashlight
  • Paper: a sheet of graph paper, or paper with a 1 cm grid drawn on it
  • A protractor
  • A pencil
  • Masking tape, to mark lines
  • 📏 A ruler

Steps

  1. Draw a grid of 1 cm squares, ten across and ten down, on a sheet of paper, or use graph paper.
  2. Tape the paper flat on a table and mark a dot in the middle.
  3. Make the room dim, so the edge of the light is easy to see.
  4. Stand the protractor on its straight edge beside the dot, and have a grown-up hold it still.
  5. Hold the flashlight at the 90 degree mark, aimed at the dot, with its glass 15 cm away.
  6. Count the squares that are more than half lit, and write the number in your table under Try 1.
  7. Tilt the flashlight to 60 degrees, keep its glass 15 cm from the dot, and count again.
  8. Tilt it to 30 degrees, keep the same distance, and count again.
  9. Do all three angles two more times, for Tries 2 and 3.
  10. Find the mean squares for each angle 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

MY RESULTSPeabody 🦉 peabody.kids/science-fair

Name ______________________ Fair day ____________

Question: Does slanted light spread wider?

I changed: Angle of the light   I measured: how many squares of the grid the light covers (squares)

Angle of the lightTry 1 (squares)Try 2 (squares)Try 3 (squares)Mean
90 degrees (straight down)
60 degrees
30 degrees

MY GRAPH (a line graph: angle of the light along the bottom, squares 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.

📊 Make my graph🖨 Print the whole packet (9 pages)

Why it works

Light that hits a surface straight on is packed into a small spot, so that spot is bright. When it arrives at a slant, the same light is spread over a bigger patch, so each square gets less. That is part of why winter is colder than summer: Earth is tilted, so in winter the sun's light reaches us at more of a slant.

Going further (7th and up): Change a second thing: keep the angle at 45 degrees and move the glass to 10, 20 and 30 cm, and graph the squares lit at each distance.

Board layout

MY BOARD · 36 × 48 in tri-foldPeabody 🦉 peabody.kids/science-fair
  1. ❓ Question (10 × 8 in): Does slanted light spread wider?
  2. 💭 Hypothesis (10 × 9 in): If I change the angle the light hits the paper, then how many squares of the grid the light covers will ______, because ______.
  3. 🧺 Materials (10 × 12 in): 5 things: see your list.
  4. 🪜 Steps (22 × 9 in): 10 steps, three tries at each level.
  5. 📊 Results (22 × 16 in): Your table (Angle of the light down the side, tries across) and your line graph.
  6. ✅ Conclusion (10 × 14 in): My hypothesis was right / partly right / not right. I know because…

Materials to list: A flashlight; Paper; A protractor; A pencil; Masking tape, to mark lines.

Bring photos or drawings of your test. Nothing wet, hot, powered or alive on the table.

This project at your grade

4th–6th gradeTries: 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 upTries: 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: keep the angle at 45 degrees and move the glass to 10, 20 and 30 cm, and graph the squares lit at each distance.

Every grade this project fits works out a mean. See every project for 5th grade, or print a blank results table.

What a judge will ask

  • What did you change, and what did you measure? I changed the angle the light hits the paper and measured how many squares of the grid the light covers, in squares.
  • What did you keep the same, and why does that matter? I kept the same flashlight and its glass the same distance from the dot each time the same, so the only difference was the angle the light hits the paper.
  • 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 keep the angle at 45 degrees and move the glass to 10, 20 and 30 cm, and graph the squares lit at each distance.

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 .

For grown-ups: Peabody has no ads, not one, and nothing to sell your child. The Kids Pick, an independent kids' directory, rates its games 90/100. See what other free kids' sites load · Grown-ups, sign in · Already have a profile?