Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 659 · 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.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
2. 2.⚖️ 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 kind of juice (c) the same cotton bud (d) the same paper
3. 3.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
4. 4.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a mirror (b) an adult with an iron (c) lemon juice (d) white paper
5. 5.True or false: white paper is needed for the secret lemon message. (a) False (b) True
6. 6.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) the ink is magnetic (c) dry juice is see-through (d) it turned into air
7. 7.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, if shaken (c) no, it stays brown (d) yes, in the dark
8. 8.⚖️ 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) False (b) True
9. 9.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a small bowl (c) a balloon (d) lemon juice
10. 10.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
11. 11.True or false: dipping the cotton bud is a job a child can do. (a) False (b) True
12. 12.True or false: a small bowl is needed for the secret lemon message. (a) True (b) False
13. 13.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a small bowl (c) a magnet (d) a cotton bud
14. 14.🔍 Which is the odd one out? (a) ironing the paper (b) putting the iron away (c) cutting the lemon (d) dipping the cotton bud
15. 15.True or false: a mirror is not needed for the secret lemon message. (a) False (b) True
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) True (b) False
17. 17.True or false: a mirror is needed for the secret lemon message. (a) True (b) False
18. 18.🧺 Which of these is not needed for the secret lemon message? (a) turmeric powder (b) lemon juice (c) white paper (d) an adult with an iron
19. 19.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
20. 20.🍋 Which of these steps is a job for an adult? (a) writing the message (b) letting the paper dry (c) dipping the cotton bud (d) cutting the lemon
21. 21.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) lemon juice (c) an adult with an iron (d) a mirror
22. 22.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) True (b) False
23. 23.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the ironing time (b) the kind of juice (c) how dark the writing is
24. 24.🔍 Which is the odd one out? (a) putting the iron away (b) dipping the cotton bud (c) writing the message (d) reading the message
25. 25.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) almost nothing (c) blue words (d) dark brown words
26. 26.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) yeast (d) an adult with an iron
27. 27.True or false: plugging in the iron is a job a child can do. (a) True (b) False
28. 28.📘 The browning of lemon juice with heat is a ___ change. (a) chemical (b) magnetic (c) musical (d) physical
29. 29.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
30. 30.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) white paper (c) a battery cell (d) lemon juice
31. 31.🍋 What colour does the lemon writing turn when an adult warms it? (a) brown (b) white (c) green (d) blue
32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is kept the same. (a) True (b) False
33. 33.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) writing turns green (c) writing stays faint (d) it gets darker
34. 34.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
35. 35.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
36. 36.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) putting the iron away (c) letting the paper dry (d) plugging in the iron
37. 37.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) yeast (c) turmeric powder (d) a small bowl
38. 38.⚖️ 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 change it (c) we measure it
39. 39.True or false: putting the iron away is a job a child can do. (a) True (b) False
40. 40.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) lick your fingers (c) skip washing (d) wash your hands

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