Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 295 · 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? What do we do with “the same paper”? (a) we change it (b) we keep it the same (c) we measure it
2. 2.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) a rainbow (c) dark brown words (d) blue words
3. 3.⚖️ 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
4. 4.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, if shaken (c) yes, if cooled (d) yes, in the dark
5. 5.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
6. 6.True or false: plugging in the iron is a job a child can do. (a) True (b) False
7. 7.True or false: putting the iron away is a job for an adult. (a) True (b) False
8. 8.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
9. 9.True or false: letting the paper dry is a job for an adult. (a) True (b) False
10. 10.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a mirror (b) a cotton bud (c) lemon juice (d) an adult with an iron
11. 11.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
12. 12.🔍 Which is the odd one out? (a) dipping the cotton bud (b) putting the iron away (c) letting the paper dry (d) reading the message
13. 13.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is magnetic (c) it is cold (d) it can burn skin
14. 14.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
15. 15.True or false: white paper is not needed for the secret lemon message. (a) False (b) True
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we keep it the same (b) we change it (c) we measure it
17. 17.True or false: a mirror is needed for the secret lemon message. (a) False (b) True
18. 18.True or false: dipping the cotton bud is a job a child can do. (a) False (b) True
19. 19.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) True (b) False
20. 20.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) writing stays faint (c) the paper floats (d) it gets darker
21. 21.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) lemon juice (c) white paper (d) a balloon
22. 22.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) dry juice is see-through (c) it turned into air (d) the paper ate it
23. 23.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we measure it (b) we change it (c) we keep it the same
24. 24.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is the one thing we change. (a) True (b) False
25. 25.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) whoever is fastest (c) the youngest child (d) only an adult
26. 26.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
27. 27.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a battery cell (c) a cotton bud (d) turmeric powder
28. 28.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
29. 29.⚖️ 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 same paper (d) the ironing time
30. 30.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
31. 31.🔍 Which is the odd one out? (a) letting the paper dry (b) cutting the lemon (c) ironing the paper (d) putting the iron away
32. 32.🍋 Which of these steps is a job for an adult? (a) reading the message (b) letting the paper dry (c) ironing the paper (d) writing the message
33. 33.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
34. 34.True or false: plugging in the iron is a job for an adult. (a) True (b) False
35. 35.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) lemon juice (c) a cotton bud (d) a magnet
36. 36.⚖️ 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 ironing time
37. 37.🔍 Which is the odd one out? (a) ironing the paper (b) putting the iron away (c) plugging in the iron (d) dipping the cotton bud
38. 38.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) lemon juice (c) yeast (d) white paper
39. 39.True or false: lemon juice is 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 the one thing we change? (a) the ironing time (b) the kind of juice (c) the same cotton bud (d) how dark the writing is

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