Science fair log book: what goes in it, with a filled-in week

A science fair log book is the diary of the project: every day you work on it, you write the date, what you did, how many tries you did and at which level, and what happened, including the surprises and the tries that went wrong. Write it on the day, in pencil, and never tidy it up afterwards. A judge reads it to see that the work happened over time and that the numbers on the board came from somewhere.

I built a tap logbook on Peabody for children who don't write much yet: three taps a day and it writes the dated entry for them. There's also a printable logbook sheet for doing it by hand. Here's what goes in either one.

Why judges ask for it

A judge can't watch the project being done. The log book is the closest thing. At one district fair whose judging procedures are public (Alpine School District, Utah, read 31 October 2026), judges score projects "based on the boards and notebooks", and the questions they're told to ask include "Show me your project notebook." At the top of the ladder, Society for Science's ISEF Display and Safety Rules (read 31 October 2026) allow a student's lab notebook at the booth and say it must be closed when the student isn't there.

So bring it to the fair, and put it on the table in front of the board.

What goes in each entry

Five things, every time:

1. The date. Every entry, even a short one. Dates in order are what show the work took days, not one night.
2. What I did. Peabody sorts every day into three kinds: got things ready, tested and wrote my numbers, or worked on my board.
3. On a test day: how many tries, and at which level. "3 tries at 20 cm." That ties each number in the results table to the day it came from.
4. What happened. It went the way I guessed; it was a surprise; or something went wrong, so I'll try again.
5. Anything odd. The window was open. The towel dried out. Someone bumped the table. These are the notes that explain a strange number later.

What doesn't go in: a neat copy of the results written at the end. The log book is allowed to be messy. Crossings-out are fine; rubbing out isn't, because a judge wants to see the first number too.

A filled-in week

Here is a week of the project Do soaked beans sprout faster? (2nd–6th grade). It tests three soaking times, not soaked, soaked 4 hours and soaked overnight, with five beans in each of nine bags, counted each day for seven days. The counts are made up for the example.

A real one would have more words in it, in the child's own spelling. Notice Thursday: a dry towel is exactly the kind of thing that explains one bag's low count, and a judge will be glad it was written down.

How the tap logbook works

Keep a project from Pick my project, then open the logbook each day you work on it:

• Tap what you did: got things ready, tested, or worked on the board.
• If you tested, tap − or + for how many tries, then tap the level you tested. The levels are your project's own.
• Tap what happened: the way I guessed, a surprise, or something went wrong.

Peabody saves it with the date and reads it out loud. A test entry comes out like this: "Friday 30 Oct: I tested and wrote my numbers: 3 tries at 20 cm. It was a surprise!" When you print it, the entries are in date order with the question at the top, followed by empty lines so the child can keep going by hand. It's kept on the device only and never sent; a grown-up can save it as a file to move it to another device.

How long should it be?

As long as the project. A one-day test still has a log book of four or five entries: getting ready, the test, the repeats, the writing and the board. A two-week plant project has one entry for every day it was checked. Peabody's plan by days, in how long a science fair project takes, shows which day is which.

Questions grown-ups ask

Can my child type the log book?

At an elementary fair, handwriting is better: it shows the child kept it. The tap logbook prints as the child's own entries, with lines underneath for handwriting. Older students at bigger fairs keep a bound notebook.

What if we forgot to write it some days?

Don't fill in the gap afterwards and pretend. Write today's date and "I forgot to write on Tuesday and Wednesday; I tested on both days." Honest is better than neat.

Does a grown-up's handwriting count?

For a kindergartner or 1st grader, a grown-up can write what the child says. Write it in their words, and let them draw the picture.

Peabody (peabody.kids) is free through the end of 2026, with no ads and no sign-up. The library has free stories by reading level for the nights the beans are just sitting there.