Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 709 · 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? True or false: how dark the writing is is what we measure. (a) False (b) True
2. 2.🍋 Which of these steps is a job for an adult? (a) plugging in the iron (b) writing the message (c) letting the paper dry (d) dipping the cotton bud
3. 3.True or false: a battery cell is not needed for the secret lemon message. (a) False (b) True
4. 4.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) a rainbow (c) dark brown words (d) blue words
5. 5.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) yeast (c) a balloon (d) lemon juice
6. 6.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the ironing time (b) how dark the writing is (c) the kind of juice
8. 8.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a balloon (c) a magnet (d) a small bowl
9. 9.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
10. 10.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
11. 11.⚖️ 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
12. 12.🍋 What colour does the lemon writing turn when an adult warms it? (a) white (b) green (c) blue (d) brown
13. 13.⚖️ 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 keep it the same (c) we measure it
14. 14.⚖️ 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
15. 15.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
16. 16.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) yes, if shaken (c) yes, if cooled (d) no, it stays brown
17. 17.True or false: a mirror is not needed for the secret lemon message. (a) True (b) False
18. 18.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) an adult with an iron (c) lemon juice (d) a magnet
19. 19.📘 The browning of lemon juice with heat is a ___ change. (a) musical (b) physical (c) magnetic (d) chemical
20. 20.⚖️ 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 same paper (c) the kind of juice (d) how dark the writing is
21. 21.True or false: letting the paper dry is a job a child can do. (a) True (b) False
22. 22.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) turmeric powder (c) a battery cell (d) a cotton bud
23. 23.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is what we measure. (a) False (b) True
24. 24.🧺 Which of these is needed for the secret lemon message? (a) an adult with an iron (b) yeast (c) a battery cell (d) a magnet
25. 25.True or false: an adult with an iron is needed for the secret lemon message. (a) True (b) False
26. 26.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) lemon juice (c) a balloon (d) an adult with an iron
27. 27.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it can burn skin (c) it is sticky (d) it is magnetic
28. 28.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) putting the iron away (c) letting the paper dry (d) ironing the paper
29. 29.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it
30. 30.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a battery cell (b) a small bowl (c) an adult with an iron (d) white paper
31. 31.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
32. 32.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) yeast (b) a cotton bud (c) an adult with an iron (d) a small bowl
33. 33.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) turmeric powder (b) an adult with an iron (c) a cotton bud (d) lemon juice
34. 34.🔮 Predict: the adult irons for only one second. What happens? (a) writing stays faint (b) it gets darker (c) the paper floats (d) writing turns green
35. 35.🍋 Which of these steps is a job for an adult? (a) reading the message (b) writing the message (c) dipping the cotton bud (d) cutting the lemon
36. 36.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same paper (b) the same cotton bud (c) the ironing time (d) the kind of juice
37. 37.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) whoever is fastest (c) any child (d) the youngest child
38. 38.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
39. 39.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
40. 40.🧺 Which of these is not needed for the secret lemon message? (a) a balloon (b) a cotton bud (c) lemon juice (d) white paper

Free science experiments lessons, practice and worksheets at talentjr.in/science-experiments-for-kids