📐 Slanted light and spot size: the whole packet

📐 Slanted light and spot size · 5th–8th grade · 1 day of testing · about $1 · 45 minutes a sitting

My days, if the fair is 14 days away

Count back from your fair day and write in each date. Fewer days than this? The jobs share days, in this order; nothing is skipped.

Dates from my teacher

• My question is due
• Testing starts
• My results table and graph are due
• My board is due

In this packet

1. 🗓️ My project plan
2. 💭 My hypothesis
3. 🧺 Change, measure, keep the same
4. 🪜 My steps
5. 📊 My results
6. 📓 My logbook
7. ✅ My conclusion
8. ✂️ Board titles to cut out
9. 🏅 The judge's questions and my certificate

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

What I think will happen, in my own words:

3 levels × 3 tries at each = 9 tries in all. If anything you keep the same changes, you won't know which change made the difference.

What I 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

Be safe: 🙅 Never at faces

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.

Write each number in your results table the moment you measure it.

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

MY GRAPH (a line graph: angle of the light along the bottom, squares up the side)

What I noticed: ______________________________________________

Write something every day you work on it, even the days you only gather things. More days? The three-page logbook prints from peabody.kids/science-fair/templates/logbook.

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: keep the angle at 45 degrees and move the glass to 10, 20 and 30 cm, and graph the squares lit at each distance.

1. What made you want to ask this question? Say something like: I wanted to know: does slanted light spread wider?
2. What did you think would happen, and why? Say something like: I thought changing the angle the light hits the paper would change how many squares of the grid the light covers, and I wrote down why.
3. What did you change, and what did you measure? Say something like: I changed the angle the light hits the paper (90 degrees (straight down), 60 degrees, 30 degrees) and measured how many squares of the grid the light covers in squares.
4. What did you keep the same, and why does that matter? Say something like: I kept the same flashlight and its glass the same distance from the dot each time the same, so only the angle the light hits the paper was different.
5. How many times did you test it? Say something like: 3 times at each of my 3 levels, and I found the middle number.
6. What did you find out? Show me in your numbers. Say something like: Look at my table: 90 degrees (straight down) and 30 degrees gave different numbers, and here's the pattern.
7. Was your hypothesis right? How do you know? Say something like: My numbers show whether I was right, partly right or not, and I can show you where.
8. Did anything go wrong, or surprise you? Say something like: One try was odd, so I did it again and wrote it in my logbook.
9. If you did it again, what would you change or test next? Say something like: I'd 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.