Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 77 · 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: cutting the lemon is a job for an adult. (a) False (b) True
2. 2.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
3. 3.⚖️ 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) how dark the writing is (c) the kind of juice (d) the same paper
4. 4.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) plugging in the iron (c) putting the iron away (d) reading the message
5. 5.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) a rainbow (c) blue words (d) almost nothing
6. 6.⚖️ 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 change it (c) we keep it the same
7. 7.True or false: reading the message is a job a child can do. (a) False (b) True
8. 8.🔍 Which is the odd one out? (a) ironing the paper (b) plugging in the iron (c) dipping the cotton bud (d) cutting the lemon
9. 9.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
10. 10.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
11. 11.🧺 Which of these is needed for the secret lemon message? (a) lemon juice (b) a battery cell (c) turmeric powder (d) a magnet
12. 12.🔍 Which is the odd one out? (a) reading the message (b) putting the iron away (c) letting the paper dry (d) dipping the cotton bud
13. 13.True or false: cutting the lemon is a job a child can do. (a) True (b) False
14. 14.🔍 Which is the odd one out? (a) letting the paper dry (b) plugging in the iron (c) reading the message (d) writing the message
15. 15.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) rub your eyes (c) wash your hands (d) skip washing
16. 16.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it is cold (c) it is sticky (d) it can burn skin
17. 17.⚖️ 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
18. 18.⚖️ 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
19. 19.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) yeast (b) lemon juice (c) a cotton bud (d) an adult with an iron
20. 20.⚖️ 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 kind of juice
21. 21.🔍 Which is the odd one out? (a) dipping the cotton bud (b) writing the message (c) ironing the paper (d) reading the message
22. 22.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a mirror (c) lemon juice (d) a cotton bud
23. 23.📘 The browning of lemon juice with heat is a ___ change. (a) musical (b) chemical (c) physical (d) magnetic
24. 24.True or false: a magnet is needed for the secret lemon message. (a) False (b) True
25. 25.True or false: a battery cell is needed for the secret lemon message. (a) True (b) False
26. 26.⚖️ 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 kind of juice (c) the ironing time
27. 27.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
28. 28.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) yeast (c) an adult with an iron (d) a cotton bud
29. 29.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) yeast (c) a cotton bud (d) turmeric powder
30. 30.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
31. 31.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) an adult with an iron (c) a cotton bud (d) a balloon
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.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) it turned into air (c) the ink is magnetic (d) dry juice is see-through
34. 34.⚖️ 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
35. 35.⚖️ 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 change it (c) we measure it
36. 36.🍋 Which of these steps is a job for an adult? (a) writing the message (b) reading the message (c) ironing the paper (d) letting the paper dry
37. 37.True or false: a balloon is needed for the secret lemon message. (a) False (b) True
38. 38.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a balloon (c) turmeric powder (d) white paper
39. 39.🔍 Which is the odd one out? (a) cutting the lemon (b) ironing the paper (c) reading the message (d) plugging in the iron
40. 40.True or false: lemon juice is needed for the secret lemon message. (a) False (b) True

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