Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 336 · 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.True or false: turmeric powder is needed for the secret lemon message. (a) False (b) True
2. 2.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) the paper floats (c) writing stays faint (d) writing turns green
3. 3.⚖️ 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 measure it (c) we change it
4. 4.🍋 Why can’t you see the lemon writing once it dries? (a) dry juice is see-through (b) the ink is magnetic (c) the paper ate it (d) it turned into air
5. 5.⚖️ 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
6. 6.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
7. 7.True or false: cutting the lemon is a job for an adult. (a) False (b) True
8. 8.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a balloon (b) lemon juice (c) a small bowl (d) a cotton bud
9. 9.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we keep it the same (b) we measure it (c) we change it
10. 10.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we change it (b) we keep it the same (c) we measure it
11. 11.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
12. 12.🔍 Which is the odd one out? (a) letting the paper dry (b) plugging in the iron (c) ironing the paper (d) putting the iron away
13. 13.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
14. 14.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we keep it the same (b) we measure it (c) we change it
15. 15.True or false: a magnet is not needed for the secret lemon message. (a) True (b) False
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is what we measure. (a) False (b) True
17. 17.True or false: ironing the paper is a job a child can do. (a) True (b) False
18. 18.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
19. 19.🔍 Which is the odd one out? (a) plugging in the iron (b) reading the message (c) cutting the lemon (d) ironing the paper
20. 20.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a battery cell (c) a small bowl (d) a balloon
21. 21.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
22. 22.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is the one thing we change. (a) True (b) False
23. 23.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a mirror (c) lemon juice (d) a battery cell
24. 24.⚖️ 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 same cotton bud (c) the kind of juice
25. 25.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) only an adult (c) the youngest child (d) whoever is fastest
26. 26.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) turmeric powder (b) lemon juice (c) a cotton bud (d) an adult with an iron
27. 27.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, in the dark (c) no, it stays brown (d) yes, if shaken
28. 28.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
29. 29.🍋 Secret message: who does this step — reading the message? (a) a child can do it (b) an adult does it
30. 30.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) False (b) True
31. 31.🔍 Which is the odd one out? (a) plugging in the iron (b) ironing the paper (c) cutting the lemon (d) dipping the cotton bud
32. 32.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
33. 33.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is what we measure. (a) False (b) True
34. 34.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
35. 35.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) chemical (c) musical (d) magnetic
36. 36.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) an adult with an iron (c) a magnet (d) turmeric powder
37. 37.⚖️ 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) how dark the writing is (c) the ironing time (d) the same paper
38. 38.🔍 Which is the odd one out? (a) reading the message (b) cutting the lemon (c) dipping the cotton bud (d) letting the paper dry
39. 39.⚖️ 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 same paper (c) how dark the writing is (d) the kind of juice
40. 40.True or false: a balloon 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