Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 771 · 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 steps is a job for an adult? (a) dipping the cotton bud (b) letting the paper dry (c) reading the message (d) cutting the lemon
2. 2.🍋 Which of these steps is a job for an adult? (a) plugging in the iron (b) letting the paper dry (c) writing the message (d) reading the message
3. 3.🔮 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
4. 4.🛟 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
5. 5.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
6. 6.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) the paper floats (c) it gets darker (d) writing stays faint
7. 7.🍋 Which of these steps is a job a child can do? (a) letting the paper dry (b) plugging in the iron (c) putting the iron away (d) cutting the lemon
8. 8.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) it turned into air (c) dry juice is see-through (d) the paper ate it
9. 9.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is cold (c) it is magnetic (d) it can burn skin
10. 10.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
11. 11.🍋 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
12. 12.True or false: ironing the paper is a job for an adult. (a) True (b) False
13. 13.🔍 Which is the odd one out? (a) dipping the cotton bud (b) ironing the paper (c) plugging in the iron (d) cutting the lemon
14. 14.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) wash your hands (c) skip washing (d) rub your eyes
15. 15.⚖️ 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
16. 16.🍋 Which of these steps is a job a child can do? (a) reading the message (b) cutting the lemon (c) putting the iron away (d) plugging in the iron
17. 17.⚖️ 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
18. 18.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) dark brown words (c) almost nothing (d) blue words
19. 19.🍋 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
20. 20.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) green (c) brown (d) white
21. 21.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) turmeric powder (c) a mirror (d) an adult with an iron
22. 22.🧺 Which of these is needed for the secret lemon message? (a) a cotton bud (b) a battery cell (c) a magnet (d) yeast
23. 23.True or false: lemon juice is needed for the secret lemon message. (a) False (b) True
24. 24.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the iron setting (b) the ironing time (c) the same paper (d) how dark the writing is
26. 26.🔍 Which is the odd one out? (a) dipping the cotton bud (b) letting the paper dry (c) reading the message (d) ironing the paper
27. 27.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
28. 28.True or false: a mirror is needed for the secret lemon message. (a) True (b) False
29. 29.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) physical (c) chemical (d) musical
30. 30.🔍 Which is the odd one out? (a) plugging in the iron (b) letting the paper dry (c) reading the message (d) writing the message
31. 31.True or false: a balloon is needed for the secret lemon message. (a) True (b) False
32. 32.⚖️ 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 measure it (c) we change it
33. 33.🔍 Which is the odd one out? (a) ironing the paper (b) cutting the lemon (c) writing the message (d) plugging in the iron
34. 34.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
35. 35.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is kept the same. (a) True (b) False
36. 36.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) putting the iron away (c) dipping the cotton bud (d) plugging in the iron
37. 37.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
38. 38.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
39. 39.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) yeast (c) lemon juice (d) a magnet
40. 40.True or false: lemon juice is not needed for the secret lemon message. (a) False (b) True

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