Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 856 · 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 is the odd one out? (a) dipping the cotton bud (b) writing the message (c) letting the paper dry (d) ironing the paper
2. 2.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) it gets darker (c) writing turns green (d) writing stays faint
3. 3.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
4. 4.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a cotton bud (c) an adult with an iron (d) a mirror
5. 5.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) whoever is fastest (c) the youngest child (d) any child
6. 6.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the iron setting (b) the same paper (c) the kind of juice (d) the same cotton bud
7. 7.🔍 Which is the odd one out? (a) ironing the paper (b) cutting the lemon (c) reading the message (d) putting the iron away
8. 8.⚖️ 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
9. 9.True or false: a battery cell is needed for the secret lemon message. (a) True (b) False
10. 10.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
11. 11.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
12. 12.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we measure it (b) we keep it the same (c) we change it
13. 13.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) it turned into air (c) the paper ate it (d) dry juice is see-through
14. 14.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
15. 15.🧺 Which of these is needed for the secret lemon message? (a) white paper (b) a magnet (c) a balloon (d) a battery cell
16. 16.🧺 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) white paper (d) a magnet
17. 17.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) reading the message (c) plugging in the iron (d) cutting the lemon
18. 18.True or false: reading the message is a job a child can do. (a) False (b) True
19. 19.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
20. 20.🧺 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 small bowl (d) yeast
21. 21.True or false: writing the message is a job for an adult. (a) True (b) False
22. 22.🔍 Which is the odd one out? (a) putting the iron away (b) plugging in the iron (c) writing the message (d) cutting the lemon
23. 23.🧺 Which of these is not needed for the secret lemon message? (a) yeast (b) a small bowl (c) a cotton bud (d) an adult with an iron
24. 24.True or false: letting the paper dry is a job a child can do. (a) True (b) False
25. 25.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
26. 26.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) a mirror (c) an adult with an iron (d) lemon juice
27. 27.🔍 Which is the odd one out? (a) ironing the paper (b) putting the iron away (c) dipping the cotton bud (d) cutting the lemon
28. 28.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
29. 29.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) wash your hands (c) rub your eyes (d) lick your fingers
30. 30.🍋 What colour does the lemon writing turn when an adult warms it? (a) white (b) green (c) brown (d) blue
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is the one thing we change. (a) True (b) False
32. 32.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) magnetic (c) musical (d) chemical
33. 33.🔮 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
34. 34.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
35. 35.⚖️ 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
36. 36.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) how dark the writing is (b) the iron setting (c) the same paper (d) the same cotton bud
37. 37.🍋 Which of these steps is a job for an adult? (a) writing the message (b) ironing the paper (c) dipping the cotton bud (d) letting the paper dry
38. 38.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
39. 39.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it can burn skin (c) it is magnetic (d) it is sticky
40. 40.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, if shaken (c) yes, in the dark (d) no, it stays brown

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