Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 458 · 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.⚖️ 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 kind of juice (c) the iron setting (d) the ironing time
2. 2.🔍 Which is the odd one out? (a) letting the paper dry (b) writing the message (c) ironing the paper (d) dipping the cotton bud
3. 3.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a balloon (b) a cotton bud (c) an adult with an iron (d) white paper
4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the kind of juice (b) the same cotton bud (c) how dark the writing is
5. 5.🧺 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 magnet (d) white paper
6. 6.True or false: turmeric powder is not needed for the secret lemon message. (a) False (b) True
7. 7.🔍 Which is the odd one out? (a) cutting the lemon (b) writing the message (c) putting the iron away (d) ironing the paper
8. 8.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) white paper (c) a battery cell (d) an adult with an iron
9. 9.⚖️ 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 measure it (c) we keep it the same
10. 10.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
11. 11.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, if shaken (c) yes, in the dark (d) no, it stays brown
12. 12.🧺 Which of these is needed for the secret lemon message? (a) a cotton bud (b) turmeric powder (c) a battery cell (d) a magnet
13. 13.True or false: ironing the paper is a job a child can do. (a) False (b) True
14. 14.True or false: a mirror is not needed for the secret lemon message. (a) False (b) True
15. 15.🔮 Predict: the adult irons for only one second. What happens? (a) writing stays faint (b) it gets darker (c) writing turns green (d) the paper floats
16. 16.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
17. 17.🍋 Which of these steps is a job a child can do? (a) reading the message (b) cutting the lemon (c) plugging in the iron (d) putting the iron away
18. 18.🔍 Which is the odd one out? (a) dipping the cotton bud (b) putting the iron away (c) plugging in the iron (d) ironing the paper
19. 19.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
20. 20.🔍 Which is the odd one out? (a) ironing the paper (b) cutting the lemon (c) letting the paper dry (d) plugging in the iron
21. 21.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
22. 22.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is what we measure. (a) False (b) True
23. 23.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a mirror (b) lemon juice (c) white paper (d) a cotton bud
24. 24.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
25. 25.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
26. 26.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) skip washing (c) wash your hands (d) rub your eyes
27. 27.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) almost nothing (c) a rainbow (d) blue words
28. 28.True or false: cutting the lemon is a job a child can do. (a) False (b) True
29. 29.True or false: yeast is needed for the secret lemon message. (a) False (b) True
30. 30.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
31. 31.True or false: an adult with an iron is needed for the secret lemon message. (a) True (b) False
32. 32.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a small bowl (c) a magnet (d) a balloon
33. 33.⚖️ 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
34. 34.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) only an adult (c) any child (d) the youngest child
35. 35.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
36. 36.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) yeast (b) a small bowl (c) lemon juice (d) white paper
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) the iron setting (c) how dark the writing is (d) the same paper
38. 38.True or false: a balloon is not needed for the secret lemon message. (a) False (b) True
39. 39.🔍 Which is the odd one out? (a) cutting the lemon (b) letting the paper dry (c) writing the message (d) reading the message
40. 40.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it can burn skin (c) it is sticky (d) it is cold

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