Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 690 · 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.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
2. 2.True or false: cutting the lemon is a job for an adult. (a) False (b) True
3. 3.True or false: a small bowl is not needed for the secret lemon message. (a) True (b) False
4. 4.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a balloon (c) lemon juice (d) a small bowl
5. 5.🔍 Which is the odd one out? (a) dipping the cotton bud (b) writing the message (c) letting the paper dry (d) putting the iron away
6. 6.🔍 Which is the odd one out? (a) putting the iron away (b) cutting the lemon (c) dipping the cotton bud (d) plugging in the iron
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we change it (b) we keep it the same (c) we measure it
8. 8.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) white paper (c) lemon juice (d) a magnet
9. 9.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False
10. 10.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) lemon juice (c) a small bowl (d) yeast
11. 11.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
12. 12.⚖️ 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 ironing time (d) the same cotton bud
13. 13.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
14. 14.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
15. 15.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) white paper (c) lemon juice (d) a battery cell
16. 16.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) any child (c) only an adult (d) whoever is fastest
17. 17.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a mirror (c) a magnet (d) a cotton bud
18. 18.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) reading the message (c) plugging in the iron (d) letting the paper dry
19. 19.True or false: yeast is needed for the secret lemon message. (a) True (b) False
20. 20.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) yes, if cooled (c) yes, in the dark (d) no, it stays brown
21. 21.🛟 Why must children keep their fingers away from the iron? (a) it can burn skin (b) it is cold (c) it is sticky (d) it is magnetic
22. 22.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is what we measure. (a) True (b) False
23. 23.⚖️ 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
24. 24.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) letting the paper dry (c) plugging in the iron (d) putting the iron away
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) True (b) False
26. 26.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) yeast (c) an adult with an iron (d) a balloon
27. 27.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a magnet (c) lemon juice (d) turmeric powder
28. 28.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we measure it (b) we change it (c) we keep it the same
29. 29.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a mirror (c) an adult with an iron (d) white paper
30. 30.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) blue words (c) almost nothing (d) dark brown words
31. 31.🧺 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) turmeric powder
32. 32.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
33. 33.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) dry juice is see-through (c) the ink is magnetic (d) it turned into air
34. 34.True or false: lemon juice is not needed for the secret lemon message. (a) False (b) True
35. 35.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) writing turns green (c) it gets darker (d) writing stays faint
36. 36.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) putting the iron away (c) dipping the cotton bud (d) cutting the lemon
37. 37.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
38. 38.🔍 Which is the odd one out? (a) putting the iron away (b) cutting the lemon (c) letting the paper dry (d) ironing the paper
39. 39.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a balloon (c) turmeric powder (d) white paper
40. 40.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a battery cell (c) lemon juice (d) an adult with an iron

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