Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 61 · 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.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) a rainbow (c) almost nothing (d) blue words
2. 2.True or false: putting the iron away is a job a child can do. (a) True (b) False
3. 3.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) the youngest child (c) only an adult (d) any child
4. 4.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a cotton bud (c) lemon juice (d) a mirror
5. 5.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we measure it (b) we keep it the same (c) we change it
6. 6.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) wash your hands (c) lick your fingers (d) rub your eyes
7. 7.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) white paper (c) a small bowl (d) a balloon
8. 8.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a small bowl (c) lemon juice (d) a balloon
9. 9.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) how dark the writing is (b) the ironing time (c) the same cotton bud (d) the kind of juice
10. 10.True or false: putting the iron away is a job for an adult. (a) False (b) True
11. 11.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a battery cell (c) an adult with an iron (d) a small bowl
12. 12.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
13. 13.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) lemon juice (c) a small bowl (d) a mirror
14. 14.True or false: lemon juice is needed for the secret lemon message. (a) False (b) True
15. 15.🍋 Why does the lemon writing turn brown with heat? (a) the juice scorches first (b) paper turns lemony (c) heat adds colour (d) the iron is brown
16. 16.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a magnet (c) a small bowl (d) white paper
17. 17.🔍 Which is the odd one out? (a) ironing the paper (b) dipping the cotton bud (c) plugging in the iron (d) cutting the lemon
18. 18.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
19. 19.True or false: a battery cell is not needed for the secret lemon message. (a) True (b) False
20. 20.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) dry juice is see-through (c) the ink is magnetic (d) it turned into air
21. 21.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
22. 22.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
23. 23.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
24. 24.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is what we measure. (a) True (b) False
26. 26.⚖️ 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
27. 27.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) an adult with an iron (c) turmeric powder (d) a battery cell
28. 28.⚖️ 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
29. 29.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the iron setting (b) how dark the writing is (c) the kind of juice
30. 30.🧺 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 magnet
31. 31.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) blue (c) white (d) brown
32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is what we measure. (a) True (b) False
33. 33.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a small bowl (c) a mirror (d) a balloon
34. 34.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
35. 35.True or false: writing the message is a job for an adult. (a) False (b) True
36. 36.🔮 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
37. 37.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) musical (c) chemical (d) magnetic
38. 38.🧺 Which of these is not needed for the secret lemon message? (a) a battery cell (b) white paper (c) a small bowl (d) lemon juice
39. 39.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is what we measure. (a) False (b) True
40. 40.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) writing the message (c) reading the message (d) plugging in the iron

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