Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 147 · 40 questions

What you do (Heat shows the secret): 1. Dip a cotton bud in lemon juice and write a secret message on white paper. 2. Let the paper dry completely — the writing disappears. 3. An adult irons the paper on a low setting while you watch from a safe distance. 4. Read the brown message and wash your hands.

1. 1.🔍 Which is the odd one out? (a) putting the iron away (b) letting the paper dry (c) reading the message (d) writing the message
2. 2.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) an adult with an iron (c) white paper (d) yeast
3. 3.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we keep it the same (b) we measure it (c) we change it
4. 4.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) green (c) white (d) brown
5. 5.True or false: white paper is not needed for the secret lemon message. (a) False (b) True
6. 6.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) yeast (c) an adult with an iron (d) white paper
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we change it (b) we measure it (c) we keep it the same
8. 8.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
9. 9.True or false: cutting the lemon is a job for an adult. (a) True (b) False
10. 10.True or false: yeast is needed for the secret lemon message. (a) False (b) True
11. 11.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) putting the iron away (c) writing the message (d) reading the message
12. 12.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a small bowl (c) a mirror (d) turmeric powder
13. 13.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) turmeric powder (c) a small bowl (d) white paper
14. 14.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the same paper (b) how dark the writing is (c) the kind of juice
15. 15.📘 The browning of lemon juice with heat is a ___ change. (a) musical (b) chemical (c) physical (d) magnetic
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same cotton bud (b) how dark the writing is (c) the same paper (d) the kind of juice
17. 17.True or false: reading the message is a job for an adult. (a) True (b) False
18. 18.True or false: lemon juice is needed for the secret lemon message. (a) False (b) True
19. 19.True or false: cutting the lemon is a job a child can do. (a) False (b) True
20. 20.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
21. 21.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) wash your hands (b) lick your fingers (c) skip washing (d) rub your eyes
22. 22.🔍 Which is the odd one out? (a) ironing the paper (b) putting the iron away (c) dipping the cotton bud (d) cutting the lemon
23. 23.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we change it (b) we keep it the same (c) we measure it
24. 24.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
25. 25.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
26. 26.True or false: letting the paper dry is a job a child can do. (a) False (b) True
27. 27.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) writing turns green (c) it gets darker (d) writing stays faint
28. 28.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is the one thing we change. (a) True (b) False
29. 29.🔍 Which is the odd one out? (a) dipping the cotton bud (b) plugging in the iron (c) reading the message (d) letting the paper dry
30. 30.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is kept the same. (a) True (b) False
31. 31.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) writing the message (c) letting the paper dry (d) cutting the lemon
32. 32.True or false: a mirror is not needed for the secret lemon message. (a) True (b) False
33. 33.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is the one thing we change. (a) False (b) True
34. 34.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the kind of juice (b) the ironing time (c) the iron setting (d) how dark the writing is
35. 35.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
36. 36.True or false: a battery cell is needed for the secret lemon message. (a) False (b) True
37. 37.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) True (b) False
38. 38.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is what we measure. (a) True (b) False
39. 39.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False
40. 40.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) how dark the writing is (b) the ironing time (c) the kind of juice

Free science experiments lessons, practice and worksheets at talentjr.in/science-experiments-for-kids