Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 290 · 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.True or false: letting the paper dry is a job for an adult. (a) True (b) False
2. 2.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
3. 3.⚖️ 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
4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we keep it the same (b) we change it (c) we measure it
5. 5.True or false: cutting the lemon is a job for an adult. (a) False (b) True
6. 6.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
7. 7.True or false: putting the iron away is a job for an adult. (a) True (b) False
8. 8.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
9. 9.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) the paper floats (c) writing turns green (d) writing stays faint
10. 10.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it is magnetic (c) it can burn skin (d) it is sticky
11. 11.True or false: a battery cell is needed for the secret lemon message. (a) False (b) True
12. 12.True or false: an adult with an iron is needed for the secret lemon message. (a) False (b) True
13. 13.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) the ink is magnetic (c) dry juice is see-through (d) it turned into air
14. 14.🔍 Which is the odd one out? (a) putting the iron away (b) reading the message (c) cutting the lemon (d) ironing the paper
15. 15.📘 The browning of lemon juice with heat is a ___ change. (a) chemical (b) magnetic (c) musical (d) physical
16. 16.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
17. 17.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) an adult with an iron (c) a magnet (d) a small bowl
18. 18.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
19. 19.True or false: a magnet is not needed for the secret lemon message. (a) False (b) True
20. 20.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a balloon (b) an adult with an iron (c) a cotton bud (d) a small bowl
21. 21.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) any child (c) only an adult (d) whoever is fastest
22. 22.⚖️ 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
23. 23.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
24. 24.⚖️ 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
25. 25.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) a magnet (c) a small bowl (d) an adult with an iron
26. 26.🔍 Which is the odd one out? (a) plugging in the iron (b) letting the paper dry (c) ironing the paper (d) cutting the lemon
27. 27.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) an adult with an iron (c) lemon juice (d) a mirror
28. 28.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) lemon juice (c) turmeric powder (d) yeast
29. 29.True or false: plugging in the iron is a job a child can do. (a) True (b) False
30. 30.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) white paper (c) a cotton bud (d) yeast
31. 31.🔮 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
32. 32.True or false: plugging in the iron is a job for an adult. (a) True (b) False
33. 33.🧺 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 mirror (d) white paper
34. 34.True or false: a battery cell is not needed for the secret lemon message. (a) True (b) False
35. 35.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, if shaken (c) no, it stays brown (d) yes, in the dark
36. 36.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
37. 37.⚖️ 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 change it (c) we measure it
38. 38.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
39. 39.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a battery cell (c) a small bowl (d) lemon juice
40. 40.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) plugging in the iron (c) cutting the lemon (d) letting the paper dry

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