Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 179 · 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 is not needed for the secret lemon message? (a) a cotton bud (b) a small bowl (c) a balloon (d) white paper
2. 2.🔍 Which is the odd one out? (a) dipping the cotton bud (b) reading the message (c) letting the paper dry (d) putting the iron away
3. 3.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
4. 4.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a mirror (c) white paper (d) lemon juice
5. 5.⚖️ 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
6. 6.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) yeast (c) an adult with an iron (d) lemon juice
7. 7.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
8. 8.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) a rainbow (c) dark brown words (d) almost nothing
9. 9.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) an adult with an iron (c) a mirror (d) a cotton bud
10. 10.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) yeast (c) a battery cell (d) an adult with an iron
11. 11.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) ironing the paper (c) dipping the cotton bud (d) cutting the lemon
12. 12.🍋 Secret message: who does this step — reading the message? (a) a child can do it (b) an adult does it
13. 13.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a small bowl (c) lemon juice (d) a battery cell
14. 14.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) lemon juice (c) yeast (d) a battery cell
15. 15.⚖️ 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
16. 16.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
17. 17.🧺 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) lemon juice (d) a balloon
18. 18.🔍 Which is the odd one out? (a) reading the message (b) letting the paper dry (c) writing the message (d) ironing the paper
19. 19.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) dry juice is see-through (c) it turned into air (d) the ink is magnetic
20. 20.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a balloon (c) yeast (d) a small bowl
21. 21.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we change it (b) we measure it (c) we keep it the same
22. 22.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the iron setting (b) how dark the writing is (c) the ironing time (d) the same paper
23. 23.True or false: an adult with an iron is not needed for the secret lemon message. (a) True (b) False
24. 24.True or false: dipping the cotton bud is a job a child can do. (a) False (b) True
25. 25.📘 The browning of lemon juice with heat is a ___ change. (a) chemical (b) physical (c) musical (d) magnetic
26. 26.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we keep it the same (b) we measure it (c) we change it
27. 27.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
28. 28.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) False (b) True
29. 29.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
30. 30.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
31. 31.True or false: reading the message is a job a child can do. (a) False (b) True
32. 32.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
33. 33.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) no, it stays brown (c) yes, in the dark (d) yes, if shaken
34. 34.True or false: cutting the lemon is a job a child can do. (a) False (b) True
35. 35.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) a small bowl (c) white paper (d) turmeric powder
36. 36.True or false: lemon juice is needed for the secret lemon message. (a) True (b) False
37. 37.🍋 Which of these steps is a job for an adult? (a) putting the iron away (b) reading the message (c) letting the paper dry (d) writing the message
38. 38.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
39. 39.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) writing stays faint (c) writing turns green (d) it gets darker
40. 40.🍋 Which of these steps is a job for an adult? (a) reading the message (b) ironing the paper (c) writing the message (d) dipping the cotton bud

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