Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 378 · 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) writing the message (b) plugging in the iron (c) ironing the paper (d) cutting the lemon
2. 2.True or false: a small bowl is not needed for the secret lemon message. (a) False (b) True
3. 3.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) writing stays faint (c) it gets darker (d) the paper floats
4. 4.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a cotton bud (c) an adult with an iron (d) a battery cell
5. 5.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the ironing time (b) the same cotton bud (c) how dark the writing is (d) the iron setting
6. 6.True or false: reading the message is a job for an adult. (a) True (b) False
7. 7.🔍 Which is the odd one out? (a) letting the paper dry (b) writing the message (c) reading the message (d) cutting the lemon
8. 8.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) magnetic (c) musical (d) chemical
9. 9.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a small bowl (c) lemon juice (d) a battery cell
10. 10.⚖️ 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 measure it (c) we keep it the same
11. 11.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
12. 12.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) blue words (c) dark brown words (d) a rainbow
13. 13.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) wash your hands (c) rub your eyes (d) lick your fingers
14. 14.🍋 Which of these steps is a job for an adult? (a) writing the message (b) cutting the lemon (c) reading the message (d) dipping the cotton bud
15. 15.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) only an adult (c) any child (d) whoever is fastest
16. 16.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a small bowl (c) white paper (d) a mirror
17. 17.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we measure it (b) we change it (c) we keep it the same
18. 18.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) yeast (b) an adult with an iron (c) white paper (d) lemon juice
19. 19.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) yes, if shaken (c) yes, if cooled (d) no, it stays brown
20. 20.True or false: plugging in the iron is a job for an adult. (a) False (b) True
21. 21.⚖️ 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 same paper (c) the kind of juice
22. 22.True or false: a small bowl is needed for the secret lemon message. (a) True (b) False
23. 23.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) putting the iron away (c) ironing the paper (d) reading the message
24. 24.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
25. 25.True or false: turmeric powder is needed for the secret lemon message. (a) False (b) True
26. 26.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a cotton bud (c) turmeric powder (d) white paper
27. 27.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a magnet (b) white paper (c) lemon juice (d) a small bowl
28. 28.True or false: a magnet is needed for the secret lemon message. (a) True (b) False
29. 29.True or false: a mirror is not needed for the secret lemon message. (a) False (b) True
30. 30.True or false: an adult with an iron is not needed for the secret lemon message. (a) False (b) True
31. 31.⚖️ 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
32. 32.🔍 Which is the odd one out? (a) dipping the cotton bud (b) putting the iron away (c) ironing the paper (d) plugging in the iron
33. 33.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is kept the same. (a) False (b) True
34. 34.True or false: reading the message is a job a child can do. (a) False (b) True
35. 35.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) putting the iron away (c) dipping the cotton bud (d) plugging in the iron
36. 36.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is what we measure. (a) True (b) False
37. 37.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) it turned into air (c) dry juice is see-through (d) the paper ate it
38. 38.True or false: letting the paper dry is a job for an adult. (a) True (b) False
39. 39.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) False (b) True
40. 40.🔍 Which is the odd one out? (a) cutting the lemon (b) plugging in the iron (c) ironing the paper (d) letting the paper dry

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