Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 189 · 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 of these is not needed for the secret lemon message? (a) a cotton bud (b) a small bowl (c) turmeric powder (d) white paper
2. 2.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) the paper floats (c) writing stays faint (d) writing turns green
3. 3.True or false: a mirror is needed for the secret lemon message. (a) True (b) False
4. 4.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) paper turns lemony (c) heat adds colour (d) the juice scorches first
5. 5.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a battery cell (c) lemon juice (d) a mirror
6. 6.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a magnet (c) white paper (d) a cotton bud
7. 7.True or false: white paper is not needed for the secret lemon message. (a) True (b) False
8. 8.True or false: a magnet is needed for the secret lemon message. (a) True (b) False
9. 9.True or false: an adult with an iron is not needed for the secret lemon message. (a) False (b) True
10. 10.True or false: lemon juice is not needed for the secret lemon message. (a) False (b) True
11. 11.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we measure it (b) we change it (c) we keep it the same
12. 12.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) no, it stays brown (c) yes, in the dark (d) yes, if cooled
13. 13.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) any child (c) whoever is fastest (d) only an adult
14. 14.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) musical (c) chemical (d) magnetic
15. 15.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we keep it the same (b) we measure it (c) we change it
17. 17.🔍 Which is the odd one out? (a) putting the iron away (b) writing the message (c) plugging in the iron (d) cutting the lemon
18. 18.True or false: ironing the paper is a job a child can do. (a) True (b) False
19. 19.⚖️ 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
20. 20.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) blue words (c) a rainbow (d) almost nothing
21. 21.True or false: cutting the lemon is a job a child can do. (a) True (b) False
22. 22.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
23. 23.⚖️ 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
24. 24.⚖️ 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
25. 25.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
26. 26.⚖️ 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 kind of juice (d) the same paper
27. 27.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the kind of juice (b) how dark the writing is (c) the iron setting
28. 28.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
29. 29.🍋 What colour does the lemon writing turn when an adult warms it? (a) brown (b) blue (c) white (d) green
30. 30.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) an adult with an iron (c) a mirror (d) a battery cell
31. 31.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) plugging in the iron (c) writing the message (d) ironing the paper
32. 32.⚖️ 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) False (b) True
33. 33.🔍 Which is the odd one out? (a) cutting the lemon (b) ironing the paper (c) dipping the cotton bud (d) plugging in the iron
34. 34.🍋 Which of these steps is a job for an adult? (a) reading the message (b) dipping the cotton bud (c) letting the paper dry (d) cutting the lemon
35. 35.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
36. 36.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a small bowl (c) a battery cell (d) a cotton bud
37. 37.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
38. 38.True or false: yeast is needed for the secret lemon message. (a) True (b) False
39. 39.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) the ink is magnetic (c) it turned into air (d) dry juice is see-through
40. 40.True or false: plugging in the iron is a job for an adult. (a) True (b) False

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