Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 718 · 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.⚖️ 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) False (b) True
2. 2.🔍 Which is the odd one out? (a) dipping the cotton bud (b) letting the paper dry (c) writing the message (d) cutting the lemon
3. 3.🍋 Why can’t you see the lemon writing once it dries? (a) dry juice is see-through (b) the paper ate it (c) it turned into air (d) the ink is magnetic
4. 4.⚖️ 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) True (b) False
5. 5.True or false: a magnet is not needed for the secret lemon message. (a) False (b) True
6. 6.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) skip washing (c) wash your hands (d) lick your fingers
7. 7.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
8. 8.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
9. 9.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) blue words (c) almost nothing (d) dark brown words
10. 10.⚖️ 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) how dark the writing is (c) the ironing time (d) the same paper
11. 11.True or false: white paper is needed for the secret lemon message. (a) True (b) False
12. 12.🍋 Secret message: who does this step — reading the message? (a) a child can do it (b) an adult does it
13. 13.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
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.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a mirror (c) turmeric powder (d) lemon juice
16. 16.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a balloon (c) white paper (d) lemon juice
17. 17.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
18. 18.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we change it (b) we measure it (c) we keep it the same
19. 19.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we change it (b) we keep it the same (c) we measure it
20. 20.🔍 Which is the odd one out? (a) letting the paper dry (b) plugging in the iron (c) writing the message (d) dipping the cotton bud
21. 21.🍋 Which of these steps is a job for an adult? (a) reading the message (b) writing the message (c) letting the paper dry (d) ironing the paper
22. 22.True or false: plugging in the iron is a job a child can do. (a) False (b) True
23. 23.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
24. 24.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) any child (c) the youngest child (d) only an adult
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is what we measure. (a) True (b) False
26. 26.🔍 Which is the odd one out? (a) letting the paper dry (b) putting the iron away (c) ironing the paper (d) plugging in the iron
27. 27.True or false: turmeric powder is needed for the secret lemon message. (a) True (b) False
28. 28.🧺 Which of these is not needed for the secret lemon message? (a) a mirror (b) a small bowl (c) lemon juice (d) an adult with an iron
29. 29.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) True (b) False
30. 30.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the kind of juice (b) the same cotton bud (c) the ironing time (d) the same paper
31. 31.🔍 Which is the odd one out? (a) dipping the cotton bud (b) letting the paper dry (c) ironing the paper (d) writing the message
32. 32.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a cotton bud (c) a magnet (d) white paper
33. 33.True or false: yeast is needed for the secret lemon message. (a) False (b) True
34. 34.True or false: a mirror is not needed for the secret lemon message. (a) False (b) True
35. 35.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) white paper (c) a small bowl (d) a magnet
36. 36.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
37. 37.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) chemical (c) musical (d) physical
38. 38.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we keep it the same (b) we change it (c) we measure it
39. 39.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) white paper (c) a balloon (d) lemon juice
40. 40.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) lemon juice (c) turmeric powder (d) white paper

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