A woman in a lilac jumper studying at a desk with an open notebook

A 21-day plan · Focus

Remember what you study

For anyone studying or learning something big. Swap rereading for quick self-tests spread over days, so what you learn is still there next week.

Recall before you reread
Quiz yourself on older material
Protect your sleep
Mix your practice

Download on the App Store GET IT ON Google Play

Run it in the By Day app on iPhone or Android.

For you if

You read it, got it, and a week later it's gone.
You reread and highlight for hours, then blank on the test.
You're learning something big and want it to stick.

You’ll need

Your study notes or material.
Blank paper or a notebook.

How you’ll know

You score higher on questions about older material than in week one.
You spend less time rereading and more time recalling.
Tests start to feel less like a blank page.

What runs when

Days 1–21

Set-upChoose your subject and study time set-up, day 1
Recall before you reread required, days 1 to 21
Quiz yourself on older material required, days 3 to 21
Protect your sleep required, days 4 to 21
Mix your practiceoptional optional, day 9, day 12, day 16, day 19

Usually 3 required habits a day, never more than three. Day 1 is set-up: choose your subject and study time. Optional rows never count toward your results or a lifetime place.

Checkpoints

Day1
Set-up: choose your subject and study time. Set a reminder for it.
Day3
Recalling feels harder than rereading. That effort is what makes it stick.
Day7
Look at your quiz scores. The questions you miss show you what to study next.
Day8
Week-one check-in: a short look back, then keep going or stop. Stopping never counts against you.
Day14
Compare this week's quiz scores with week one, on material from further back.
Day21
Decide what to keep. The blank-page recall and the older-material quiz are the two to hold on to.

Why it works

Pulling something out of your memory strengthens it more than reading it again, even though rereading feels easier. Spacing that practice over days helps it last. And sleep is when your brain stores what you learned, so late cramming works against you.

Testing yourself is one of the most replicated findings in learning research: in lab studies and in real classrooms, it beats rereading for remembering material later. Spacing practice over days helps, and losing sleep hurts memory. Gains vary by material and test, so there are no promises about grades.Sources

Results

If you connect Apple Health, Health Connect or Oura, the plan adds total sleep, measured against your first nights and marked still forming until day 14. What you notice yourself is the main measure.

Before you start

No promises about grades: results depend on the material and the test.
If forgetfulness or trouble concentrating is new or getting worse, or started after an illness, with low mood, or with a new medicine, talk to a doctor.
Don't trade sleep for study: all-nighters make memory worse, not better.

Access

Now: Free, with every feature, during the open beta. No card, no end date yet.
A lifetime place: Finish your first full 21-day plan during the beta with at least 80% of its required habits done and, if fewer than 200 people have qualified before you, Explorer is yours for life straight away. Stopping early doesn’t count against you; the first plan you run to its end is the one that counts.
After the beta: One active plan, daily habits, mood, recaps and history stay free. Explorer, the paid tier, adds every plan and connected health readings.
Where: The By Day app on iPhone and Android, to run it and to look back.