Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 242 · 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.🍋 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
2. 2.⚖️ 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 iron setting (d) the same paper
3. 3.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a cotton bud (c) an adult with an iron (d) a battery cell
4. 4.True or false: a battery cell is needed for the secret lemon message. (a) False (b) True
5. 5.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) only an adult (c) any child (d) the youngest child
6. 6.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
7. 7.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a cotton bud (c) yeast (d) lemon juice
8. 8.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) skip washing (c) wash your hands (d) rub your eyes
9. 9.🔍 Which is the odd one out? (a) ironing the paper (b) plugging in the iron (c) cutting the lemon (d) letting the paper dry
10. 10.True or false: white paper is needed for the secret lemon message. (a) True (b) False
11. 11.🍋 Which of these steps is a job for an adult? (a) reading the message (b) writing the message (c) dipping the cotton bud (d) cutting the lemon
12. 12.⚖️ 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 keep it the same (c) we change it
13. 13.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
14. 14.⚖️ 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 kind of juice (c) the iron setting
15. 15.True or false: putting the iron away is a job a child can do. (a) True (b) False
16. 16.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) dark brown words (c) blue words (d) a rainbow
17. 17.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a mirror (b) white paper (c) a cotton bud (d) a small bowl
18. 18.🧺 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 magnet
19. 19.🍋 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) writing the message
20. 20.🔍 Which is the odd one out? (a) ironing the paper (b) cutting the lemon (c) writing the message (d) putting the iron away
21. 21.True or false: writing the message is a job a child can do. (a) False (b) True
22. 22.⚖️ 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 ironing time (d) how dark the writing is
23. 23.True or false: a cotton bud is needed for the secret lemon message. (a) False (b) True
24. 24.⚖️ 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
25. 25.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) white paper (c) a mirror (d) turmeric powder
26. 26.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
27. 27.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) yes, if cooled (c) no, it stays brown (d) yes, if shaken
28. 28.True or false: a mirror is not needed for the secret lemon message. (a) True (b) False
29. 29.🍋 Which of these steps is a job for an adult? (a) writing the message (b) reading the message (c) dipping the cotton bud (d) putting the iron away
30. 30.True or false: putting the iron away is a job for an adult. (a) True (b) False
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) True (b) False
32. 32.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) putting the iron away (c) ironing the paper (d) dipping the cotton bud
33. 33.True or false: dipping the cotton bud is a job for an adult. (a) False (b) True
34. 34.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) cutting the lemon (c) letting the paper dry (d) plugging in the iron
35. 35.🔍 Which is the odd one out? (a) cutting the lemon (b) reading the message (c) ironing the paper (d) putting the iron away
36. 36.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) lemon juice (c) turmeric powder (d) a magnet
37. 37.True or false: cutting the lemon is a job for an adult. (a) False (b) True
38. 38.🍋 What colour does the lemon writing turn when an adult warms it? (a) white (b) blue (c) green (d) brown
39. 39.True or false: an adult with an iron is not needed for the secret lemon message. (a) False (b) True
40. 40.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False

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