Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 578 · 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.⚖️ 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
3. 3.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we measure it (b) we change it (c) we keep it the same
4. 4.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
5. 5.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
6. 6.True or false: a magnet is not needed for the secret lemon message. (a) False (b) True
7. 7.🧺 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 cotton bud (d) turmeric powder
8. 8.🔍 Which is the odd one out? (a) reading the message (b) cutting the lemon (c) writing the message (d) letting the paper dry
9. 9.True or false: a magnet is needed for the secret lemon message. (a) False (b) True
10. 10.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False
11. 11.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
12. 12.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a cotton bud (c) a mirror (d) a balloon
13. 13.⚖️ 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
14. 14.⚖️ 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
15. 15.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same cotton bud (b) the iron setting (c) the same paper (d) how dark the writing is
16. 16.True or false: a cotton bud is needed for the secret lemon message. (a) True (b) False
17. 17.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, if shaken (c) yes, in the dark (d) yes, if cooled
18. 18.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a balloon (c) white paper (d) an adult with an iron
19. 19.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a balloon (c) a small bowl (d) a magnet
20. 20.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) False (b) True
21. 21.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) an adult with an iron (c) a mirror (d) lemon juice
22. 22.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) blue (c) white (d) brown
23. 23.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
24. 24.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
25. 25.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) a mirror (c) white paper (d) lemon juice
26. 26.🧺 Which of these is needed for the secret lemon message? (a) white paper (b) a balloon (c) a magnet (d) yeast
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) the ironing time (c) how dark the writing is
28. 28.🛟 Why must children keep their fingers away from the iron? (a) it can burn skin (b) it is cold (c) it is magnetic (d) it is sticky
29. 29.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a battery cell (c) a small bowl (d) an adult with an iron
30. 30.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it
31. 31.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a cotton bud (c) white paper (d) a magnet
32. 32.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
33. 33.True or false: plugging in the iron is a job a child can do. (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 is the odd one out? (a) reading the message (b) writing the message (c) letting the paper dry (d) plugging in the iron
36. 36.🧺 Do we need a battery cell 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 “how dark the writing is”? (a) we keep it the same (b) we change it (c) we measure it
38. 38.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) dipping the cotton bud (c) reading the message (d) ironing the paper
39. 39.True or false: white paper is needed for the secret lemon message. (a) True (b) False
40. 40.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed

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